NAND array architecture for multiple simutaneous program and read

ABSTRACT

This invention discloses a HiNAND array scheme with multiple-level of bit lines (BLs) including metal3 global bit lines (GBLs), divided metal2 Segment bit lines (SBLs), and divided metal1 block bit lines (BBLs) laid out in parallel to each other respectively for a plurality of NAND Strings. All other source lines or power lines connected to bottoms of corresponding String capacitances of GBLs, SBLs, and BBLs are associated with metal0 line laid out perpendicular to those BLs. Under the HiNAND array scheme, conventional one-WL Read and Program-Verify operations are replaced by multiple-WL and All-BL Read and Program-Verify operations executed with charge capacitance of SBLs being reduced to 1/10- 1/20 of capacitance of GBLs to achieve DRAM-like faster operation, less operation stress, and lower power consumption. A preferred set of program biased voltages on the selected WL and remaining non-selected WLs associated with a Multiplier and a DRAM-like charge-sharing Latch Sensing Amplifier is proposed.

1. CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/840,020, filed Jun. 27, 2013, commonly assigned and incorporated byreference herein for all purposes.

Additionally, this application is related to U.S. Pat. Nos. 7,440,318,7,570,517, RE43,665 E, and 7,262,994, which are incorporated byreference herein for all purposes.

This application is further related to an article titled “A 3.3V 128 MbMulti-Level NAND Flash Memory for Mass Storage Applications” by Tae-SungJung, etc., Samsung Electronics, Solid-State Circuits Conference, Feb.10, 1996. Digest of Technical Papers. 42nd ISSCC. 1996 IEEEInternational, page 32-33; and an article titled “A 1.8V 2 Gb NAND FlashMemory for Mass Storage Applications” by June Lee et al., IEEE JSolid-State Circuits, vol. 38, No. 11, November 2003, pp. 1934-1942.

2. BACKGROUND OF THE INVENTION

This invention relates generally to all 2D and 3D NAND arrayarchitecture circuits. In particular, the present invention providesHiNAND array architecture circuits that include several preferred newcircuits such as Segments and Groups into the NAND array along with afeature of circuit migration from conventional one-Block-one-rowselection of Page Buffer, Sense Amplifiers, and Block-decoders inState-machine design to multiple Programs and Reads inMultiple-Block-Multiple-Rows in different Planes.

Nonvolatile memory (NVM) is well known in the art which provides thein-system or in-circuit repeatedly electrically programmable anderasable functions. So far, NVMs include three major standalone typessuch as EEPROM, NOR, and NAND Flash memory and one embedded type Flash(eFlash) memory. All above four NVMs are based on varied technologies.

The EEPROM is suitable for the Byte-alterable Data storage with thehighest density below 4 Mb at 0.13 um node. The NOR flash is suitablefor the block-alterable Code storage with the highest density below 8 Gbat 45 nm node. The eFlash is suitable for the page-alterable Codestorages with the highest density below 64 Mb at 65 nm node. Lastly,NAND flash is suitable for the Segment-alterable Data storage with thehighest density below 256 Gb at 19 nm node in MLC storage.

Currently, NAND flash memory has achieved the highest scalability,density and smallest feature of 1×nm node since 2012. The mainstreamstandalone NAND in mass production is mainly based on 2-polyfloating-gate NMOS device, which employs 20V but the extremely lowcurrent FN channel-erase and FN channel-program schemes.

The NAND flash cell array comprises a plurality of NAND Strings that areorganized in a matrix as a Plane with a plurality of rows and columns.Each NAND String is further comprised of a plurality of NMOS NAND cellsconnected in series sandwiched by two NMOS 1-poly String-selecttransistors, for example, MS located on top of the String and MG onbottom of the String. The number of NAND flash cells in one String canbe made of 8, 16, 32, 64, 128 or arbitrary integer number, depending onNAND density requirement and applications. Each NAND cell has severaldifferent types of storages that include SLC (1 bit per cell), MLC (2bits per cell), TLC (3 bits per cell), XLC (4 bits per cell) and evenanalog storage that stores more than 4 bits per NAND cell.

Today, a typical extremely high-density, nGb, NAND flash arrayarchitecture is comprised of a plurality of NAND Planes cascaded in rowsin X-direction and columns in Y-direction. The number of rows andcolumns of each NAND Plane can be 2, 4 or 8 or more and is optimallydetermined by the trade-off of the chip layout and performance.

Each NAND Plane is further comprised of a plurality of NAND Blocks thatare then physically cascaded one-by-one in the Y-direction and each NANDBlock is further comprised of a plurality of NAND Strings cascaded in arow in the X-direction. Each NAND String includes a plurality of NANDcells, for example, M cells connected in series and sandwiched by onetop String-select transistor and one bottom String-selected transistor.The value of M can be 8, 6, 32, 64, 128 or any arbitrary integer number,depending on the NAND specs and applications. The numbers of optimalPlanes, Rows, Blocks and Strings are fully determined by the trade-offof the design factors such as the optimal chip size, chip performance,design features and reliability concerns of the NAND flash memory.

In the exemplary case of 1-row and 2-plane NAND flash memory, the mainNAND Plane-decoder is preferably placed in the middle of the NAND arraybetween left and right NAND Planes. The Block-decoder can be flexiblyplaced in the middle of the NAND array between two horizontal NANDPlanes in one row so that each Block-decoder's multiple outputs can beused to drive the multiple selected word lines (WLs) of one selectedcorresponding NAND Strings placed either in left or right Plane.

In optimal layout, two big independent PBs (Page-Buffers) and SA (SenseAmplifier) circuit blocks are physically placed right on top of left andright NAND Planes across whole NAND array in the X-direction. The PB mayinclude multiple latches with inputs and outputs to store the data readfrom the corresponding bit lines (BLs) of NAND flash cells or from theexternal data lines.

For the array organization of a 2-plane, 1-row NAND flash memory with acondition that only one Plane can be selected at a time for Read,Program, Program-Verify and Erase-Verification, then only group ofBlocks are selected either from the left or right NAND Plane. If thearray design allows two NAND planes to be selected simultaneously, thentwo groups of Blocks of both left and right Planes can be selected with2-fold faster speed of Read and Program operations.

For the array organization of a 1-plane, 1-row NAND flash memory, thenthe Block-decoder is preferably placed in one end of the NAND array. Insuch a layout arrangement, the Block-decoder's multiple outputs can beused to drive the multiple selected WLs in the selected correspondingStrings of the select Block of NAND memory.

There exist other NAND array organizations such as NM matrix of N rowsand M Planes. Nevertheless, unless each Plane has its own PB circuit,multiple Blocks in different NAND Planes in different rows cannot beselected because PB and BLs are shared by all NAND Blocks cascadedvertically in the Y-direction. The operation of the selected Blocks inthe same row of the selected NAND Plane has to be done sequentially oneby one to avoid the data contention in BLs and PB.

Now, key Program operation of a conventional NAND is explained below viaFIG. 1 and FIG. 2. FIG. 1 shows a typical NAND array with one portion ofBlock and one Sense Amplifier (SA) shared by one paired NAND Stringssuch as one Odd String with its drain node coupled to BLo metal bit lineand one Even String with its drain node coupled to another BLe metalline. The whole NAND Block memory comprises a plurality of pairs of BLeand BLo (although only one pair of BLe and BLo is shown). In thisexample, the SA contains one Sensing and Precharging circuit and oneLatch circuit for SLC Program and Read operation.

This NAND array has one metal line (metal0) for common source line (CSL)and another metal line (metal1) with an x-pitch size of 2λ for both BLeand BLo. The BLe and BLo are like GBL (global bit line) running fromNAND array top and are connected the outputs of PB to the array bottomwithout being divided into a plurality of divided-BLs such as local bitlines (LBLs). In other words, along BL or a column in Y-direction in thearray layout, the NAND array is made of a single metal1 NAND array.

In each BLo or BLe, it directly connects to a plurality of NAND Strings.Each NAND String, in this example, comprises 32 2-poly NMOS NAND cellsconnected in series sandwiched by one top 1-poly NMOS String-BL-selecttransistor MSe in BLe or MSo in BLo, gated by a common signal of SLL,and one bottom 1-poly NMOS String-SL-select transistor, MG1 in BLe orMG2 in BLo, gated by another common signal of GSL. The 32 NAND gates ofeach String are connected to 32 WLs such as WL[1] to WL[32].

Besides the NAND array, one sensing Latch circuit per each pair of BLeand BLo with PRESET, PLOAD, and PBLCH control signals for Program-Verifyfunction are also shown in FIG. 1. Since one pair of BLo and BLe sharesone sensing Latch circuit comprising two invertors INV1 and INV2, thusonly one NAND String in either BLo or BLe is selected for Read operationin this NAND array. Therefore this conventional NAND array and sensingLatch circuit do not offer ALL-BL Read. In other words, to read a wholephysical page requires two sub-steps to read either BLe group first andthen BLo group later or vise versa.

Furthermore, in this conventional NAND array, only two Strings are shownwith one pair of BLo and BLe. In fact, a full NAND array includes up to4 KB pairs of BLo and BLe lines per WL or per physical page with a 8 KBsize. Similarly, there are pluralities of NAND Strings in each BLo andBLe. The number of NAND Strings is subject to the required NAND density.

The so-called All-BL Program operation means that the Program size isone physical page and is performed in 1-cycle. But an Odd/Even pageProgram operation means that the Program operation is performed in unitof a logic page which is half of whole physical page. The whole physicalProgram operation needs a 2-cycle Read operation of two half-pageProgram operations. Programming bias conditions are summarized below:

-   -   a) Selected Flash cells' gate voltage WL in selected page to        Vpgm ranging from 15V to 25V with Incremental Step Pulse        Programming (ISPP) scheme and ΔVpgm ranging from 0.15V to 0.2V        for MLC-type and TLC-type storage.    -   b) Selected Flash cell's channel voltage to 0V. This 0V is        coupled from the corresponding bit data=0 in Page Buffer. The 0V        is coupled to the NAND cells of the selected WL through a NMOS        BL-Select transistor that is turned on in a conduction state.        The advantage of Program BL=0V lies in that no BL precharge        current is required.    -   c) Unselected Flash cells' channel voltage V_(Inhibit)≧7V for        Program-Inhibit operation. This V_(Inhibit) voltage is generated        by WL-gate coupling effect to boost the initial floating channel        voltage of Vdd-Vt of bit data=1 in Page Buffer to 7V of        unselected NAND cells in the same selected page or WL. This is        referred as a Self-Boosting (SB) effect. The disadvantage        Program-Inhibit BL=Vdd lies in that multiple high BL precharged        currents are required because it needs to change the selected BL        to Vdd.    -   d) NAND Program scheme: A low current FN channel tunneling        effect to increase NAND cell's Vt from E state (erased state) to        three program states such as A, B, or C state for a MLC storage.    -   e) Program-Inhibit voltage generation methods include SB, LSB        and EASB.

In a typical NAND Program operation, a high step-rising program voltage,Vpgm, ranging from 15V to 25V, is applied to one selected WL[m], but aVpass (program) voltage of around 10V is applied to the rest of 31(assuming total 32 WLs in each Block) non-selected WLs in the selectedStrings along with the gate of bottom String-select transistor connectedto Vss and the gate of top String-select transistor connected to Vdd.

As a result, 31 NAND cells in same String are in conduction-state whilethe String's bit line is grounded. The plurality of electrons from theselected NAND cells'channels are injected into the floating gate layer,Poly1, and NAND cells' threshold voltage, Vt, are raised from an erasedVt0 at E-state with a negative value to a desired positive value of Vt1referred to a first programmed state, A-state.

More information about the programming methods can be found in U.S. Pat.No. 6,859,397, titled “Source Side Boosting Technique for Non-volatileMemory;” and U.S. Pat. No. 6,917,542, titled “Detecting Over ProgrammedMemory;” and U.S. Pat. No. 6,888,758, titled “Programming Non-VolatileMemory.”

In many cases, Vpgm pulse is applied to the selected WL[m] of NANDassociated with several MHV pass-WL voltages such as Vpass (program)voltages, Vpass1, Vpass2, and others, applied to the non-selectedWL[m−1] and WL[m+1] and the rest of WL[m] in the selected NAND Stringsof the selected Blocks.

A series of Vpgm pulses (referred to as the programming gate pulses),with the magnitude of the pulses increasing are applied to WL[m].Between each rising-step Vpgm pulse, a set of single or multiple ProgramVerify pulses like Read operation are performed to determine whether theselected NAND cells(s) in the selected page or WL are being programmedinto the desired programmed Vtn values. The programmed Vtn values aredetermined by the type of storages such as SLC (1-bit per cell), MLC(2-bit per cell), TLC (3-bit per cell), XLC (4-bit per cell) or analogstorage (more than 4-bit per cell).

Since Program-Verify operation is like the regular Read operation, thepreviously mentioned BL-precharge cycle and discharge cycle would be thesame. Therefore, during each Program-Verify cycle, a NAND flash memoryhas to precharge all long BLs' large capacitance from Vss to VBL asdescribed before. As a result, a large BL precharge current occurs andthe large Vpass (read) 6V WL disturbance will be induced on NAND cell.In addition, Program-Verify cycle also has a long latency as Read due tothe discharge process starts from a high value of V_(BL), which rangesfrom 0.8V to Vdd in today's NAND design.

If any of the selected NAND cells have reached their targeted programmedVts as determined in Program-Verify step, then the further programs haveto be stopped on those NAND cells to avoid over-programming into a nexthigher wrong Vt state. For those NAND cells' Vts that do not reach thedesired value after Program-Verify operation, then the Vpgm pulsescontinue applying to those NAND cells in the selected page or WLassociated with Vpass voltage of 10V or other HV to the non-selectedWLs. If the desired Vts are not reached, then the programming and verifypulses would be repeatedly applied to those cells. Until all NAND cellsin the selected page have been programmed successfully into the desiredVt states, then the Program and Program-Verify operations of theselected page would be stopped. The Program and Program-Verifyoperations would be continued on those remaining pages in the preferredsequence from String bottom to the String top in the selected Strings ofthe selected Blocks of the NAND memory. As the Program andProgram-Verify operations repeat, the BL precharge current and VpassWL-induced disturbance will be multiplied.

Typically, each NAND string physically comprises 16, 32, 64, or even 128WLs. The MLC page number is doubled to SLC page number, TLC density istripled, and XLC density is quadrupled.

A multi-state NAND memory device stores multiple bits of data per NANDcell by differentiating multiple distinct valid Vtn distributionsseparated by some preferred forbidden ranges such as ΔVtn. Each distinctVtn has a distribution between Vtn_(max) and Vtn_(min). Each ΔVtn isdefined to be a value of Vtn_(min) of a higher-level state minus theVtn_(max) of a lower-level Vtn state. Each Vtn is defined correspondingto a predetermined value for the set of data bits encoded in NANDdevice. As the number of bits of data per NAND cell is increased fromSLC to MLC, TLC, and XLC, the number of valid Vtn states increases from2 to 4, 8 and 16. As a result, the NAND data capacity is drasticallyincreased, thus the die cost is greatly reduced.

There is a tradeoff. When each NAND cell storage capacity is programmedto increase, however, the programming time also increases and NANDcell's data reliability greatly degrades accordingly. In someapplications, the increased programming time and the lower datareliability cannot be accepted.

Below, the conventional NAND Read and Program-Verify operations will beexamined in term of Read disturbance, Read cycle, Read current and Readlatency. FIG. 2 shows some typical time lines of some key controlsignals for properly operating the conventional NAND array as seen inFIG. 1. These key control signals include BLSHF, PBRST, PLOAD, SO & BLeor SO & BLo, PBLCH, Node A, WL (Selected one) and WLs (unselected 31ones), etc for operating BL precharge and discharge, charge up of oneselected WL and 31 unselected WLs, and proper control sequences for NANDdata sensing and latch function for SLC Read. For each Read operation, apredetermined V_(RD) voltage is applied to the selected WL and the aWL-pass voltage Vpass ranging from 5 to 7V is applied to the unselectedN−1WLs to turn the N−1 NAND cells into the conduction state so that theOn state or Off state of the selected NAND cells can be accuratelydistinguished. The single V_(RD) value of 0V is used for a SLC Read. Butthree distinct V_(RD) values of 0V, 1.5V, and 3V are for a MLC Read and7 distinct V_(RD) values are used for TLC Read and 15 distinct V_(RD)values are used for XLC Read.

Since each SLC Read from NAND String, all the non-selected cells in thenon-selected WLs or pages suffer Vpass WL disturbance. For MLC Read, itwill suffer 3 times Vpass WL disturbance, for TLC Read it will suffer 7times Vpass WL disturbance, and for XLC Read it will suffer 15 timesVpass WL disturbance. As a result, the Vpass WL disturbance becomes moresevere issue in NAND memory with higher storage compression. Inaddition, each Read of NAND programmed states of A, B and C wouldconsume one high BLn precharge current.

Today, the averaged Read latency is 20 μS per page but Program latencyis 200 μS for SLC Program and 600 μS is for MLC Program. Both Read andProgram operations can only be performed in unit of whole physical pagein one cycle or two-cycle Read for Odd and Even logic pages. All thisRead and Program specs have not changed for 25 years. But when NANDtechnology is scaled down below 2×nm and the density being increasedabove 256 Gb, the above slow Read and Program latency becomesunacceptable for fast memory system applications. In addition, thehigh-power consumption and low P/E and Read cycles are getting theconcerns.

As a result, it is highly desired to reduce Read and Program latency andpower consumption and to increase the NAND reliability, P/E and Readcycles so that the less-sophisticated Error Correction Coding (ECC), DSPand Flash management tolls of Flash controller can be used at a lowercost. As an attempt to improve in this aspect, the present inventionprovides a HiNAND array adopting multiple-level BL architecture and aNon-Self-Boosting-Program-Inhibit method (Non-SBPI) along with othercircuits such as Multiplier and XOR-Comparator to achieve the fastermultiple-WL and All-BL Program and Read operations.

3. BRIEF SUMMARY OF THE INVENTION

This invention relates generally to all 2D and 3D NAND arrayarchitecture circuits. In particular, the present invention providesHiNAND array architecture circuits that include several preferred newcircuits such as Segments and Groups into the NAND array along with afeature of circuit migration from conventional one-Block-one-rowselection of Page Buffer, Sense Amplifiers, and Block-decoders inState-machine design to multiple Programs and Reads inMultiple-Block-Multiple-Rows in different Planes.

In an embodiment, the present invention provides a HiNAND2 array thatcomprises a 2-level BL-hierarchical structure that uses a group ofmetal2 lines for a plurality of global bit lines (GBLs) and anothergroup of metal1 lines for a plurality of sub-bit lines (SBLs) inparallel to the group of metal2 lines and one more group of metal0 lineslaid perpendicular to both metal1 and metal2 lines for all power or Vsslines such as source lines of NAND Strings, or source lines of aplurality of bottom BL-select (MSBL) transistors. The HiNAND2 is notshown in a separate figure but is substantially the similar to a 3-levelHiNAND3 only with metal3 lines for divided BLs being removed.

In another embodiment, the present invention provides a HiNAND3 arraythat comprises a 3-level BL-hierarchical structure that uses a pluralityof metal3 lines respectively for a plurality of GBLs and anotherplurality of metal2 lines respectively for a plurality of sub-BL lines(SBLs) and yet another plurality of metal1 lines respectively for aplurality of sub-sub-BL lines (BBLs), all these metal3, metal2, andmetal1 lines are parallel to each other. The HiNAND3 array alsocomprises a plurality of metal0 lines laid perpendicular to metal1 linesfor all power or Vss lines such as the source lines of NAND String, orthe source line of a plurality of bottom BL-select (MSBL) transistorsand top BL-select (MBBL) transistors.

In yet another embodiment, the present invention provides a HiNAND arraythat comprises a plurality of NAND Groups, a plurality of Segments laid1-level down, and a plurality of Blocks laid 2-level down. Each Blockcomprises a plurality of NAND Strings and each NAND String furthercomprises 16, 32, 64, 128 or any integer number of NAND cells connectedin series with top and bottom String-select transistors. Besides to havea n-level BL-hierarchical structure, a SL-hierarchical structure is alsopreferably with one pair of NMOS devices MBBL and MSBL formed on each ofthe divided BLs such as a SBL and a BBL in addition to the conventionalString SLs.

In still another embodiment, the present invention provides a HiNANDarray that comprises a LV GBL-Page Buffer (GBL-PB) circuit along withn-level BL-hierarchical structure with a desired local lowest levelBL-capacitance to allow the temporary storages of Vss program voltageand V_(Inhibit) program-inhibit voltage for the desired multiple-WLProgram and Read operations. The V_(Inhibit) voltage is Vdd or 7Vhigher.

In yet still another embodiment, the present invention discloses aHiNAND3 array that comprises a plurality of BBL parasitic capacitors andeach BBL has one NMOS BL-select transistor MBBL that is intended tocouple a middle level voltage up to V_(Inhibit) voltage ˜7V from aselected corresponding horizontal line BBLps for saving the powerconsumption for precharging BBLs to 7V. This V_(Inhibit) voltage ofabout 7V is not coupled from the array top LV GBL-PB that would consumestoo much current due to long and heavy parasitic GBL capacitance.

In an alternative embodiment, the present invention discloses a HiNAND3array with a preferred set of the program-bias voltage conditions forprogramming the NAND cells of the selected Block in series with onesingle selected WL, Vpgm, and (M−1) non-selected WLs with Vpass1, Vpass2and others. The value of M=32 for 32T-String HiNAND array or M=64 for a64T-String HiNAND array, although other number is also theoreticallypossible. Assuming the programming start from the String bottom WL[M]serially to the String top WL[1], the preferred set of WL biasconditions includes setting the selected WL[m] to Vpgm, and setting alast WL[m+1] to Vpass2=10V to reduce the WL-WL punch-through voltage,and setting other WL[m+2]= . . . =WL[M]=Vdd for those NAND cells beingprogrammed already but setting WL[m−1]= . . . =WL[1] to Vpass1=7V forthose NAND cells not yet being programmed with erased Vts of −0.7V,where M=32 for a 32T-String in the HiNAND3 array or M=64 for a64T-String in the HiNAND3 array. All NAND cells connected from WL[m−1]above the selected word line to WL[1] on the top end of a NAND Stringare associated with threshold voltages Vts equal to an erased Vt whichis smaller than −0.7V.

In another alternative embodiment, the present invention provides aHiNAND array with each optimized Sub-BL capacitance being about 1/10 or1/20 of each GBL-capacitance to allow fast All-BL one full physical-pageRead operation. The traditional Read operation of conventional NANDprecharges and discharges all long and heavy GBL lines (with largeGBL-capacitances) using a Vdd-Vt voltage that consumes too much Readpower current and suffers slower Read latency and more BL-BL couplingnoise. Instead of that, this HiNAND array is configured to onlyprecharge and discharge lighter local SBL-capacitance, thus leading toless Read disturbance, lower power consumption and Read latency withnear-zero BL-BL coupling noise.

In yet another alternative embodiment, the present invention provides apreferred set of bias voltage conditions for the fast multiple-WL &All-BL Program, Program-Inhibit, Program-Verify, and Read operations forthe HiNAND array. Note, each WL Program or Read voltage can be performedin unit of All-BL structures with less power and disturbance than thatfor the conventional NAND array which can be programmed and read in onlyone WL size.

In still another alternative embodiment, the present invention providesan improved technique to allow flexible setting or resetting of eachlatch of each Block-decoder. In the conventional NAND architecture onlyone latch of Block-decoder is set to select one WL in one selected Blockfor Program and Read operations. In this HiNAND array, a newBlock-decoder is configured to allow flexibility to set and resetmultiple latches for the desired multiple-WL & All-BL simultaneous Read,Program-Verify, and Program operations.

The Program operation is preferably to be a serial Program scheme and isperformed on the same locations of selected WLs on multiple selectedBlocks preferably located in different Segments. The program sequence ofHiNAND is preferably identical to that of the conventional NAND arrayfrom the bottom cell to the top cell of NAND String of one Block. Themultiple-WL Read is to allow the random Read on all selected multipleWLs on multiple Blocks preferably in different Groups. One method ofreading the same location of the selected WL in different Blocks in thedifferent Segments and Groups is proposed. But traditional page data inmultiple WLs in the same Block is preferably disposed in the same pagelocation or WL in the different Segments so that the goal of random Readin NAND memory can be better retained in this preferred Multiple-WL andAll-BL Read operation.

In a specific embodiment, the present invention discloses a techniquefor single LV GBL-PB to store m-page temporary data for M multiple-WL &All-BL Program and Program-Verify operations. The m-page is preferablyto have more than one page but the value of m<M for an optimal PB size.The page data is preferably serially or parallelly loaded into this PBfrom off-chip Flash controller in a pipeline method. The page data canbe in any storage form such as SLC, MLC, TLC and XLC or even 256-levelAnalog format.

In another specific embodiment, the present invention provides atechnique for single LV GBL-PB to store K-page temporary data for M-WL &All-BL Program and Program-Verify operations. The K-page is preferablyto have more than one page but the value of K<M for an optimal PB size.Additional pages of PB are used to temporarily store the K pages of reador program-verified page data and then be serially or parallelly loadedinto I/O bus and read in pipeline form by off-chip Flash controller. Asa result, the on-chip PB size can be reduced for this preferredMultiple-WL & All-BL Program, Program-Verify, and Read operations.

In yet another specific embodiment, the present invention discloses atechnique for increasing speed of precharge and discharge of GBL throughadded 7V NMOS devices of MBBLs for each Segment or MSBLs for each Group.In the conventional NAND, the precharge and discharge of GBL has to gothrough one HV (20V) NMOS device with a much thicker gate (>300 A) andlonger channel length per GBL. Now, a 7V NMOS device with thinnergate-oxide and shorter channel length can reduce the precharge anddischarge time of GBL and reduce SBL and BBL lines and associatedcapacitances.

In still another specific embodiment, the present invention discloses apreferred Non-SBPI method to achieve a least Vpass WL program stress fora longer P/E cycles.

In an embodiment, the present invention provides a high-density NAND(HiNAND) circuit with multi-level BL-hierarchical architecture forlowering disturbance, power-consumption, and latency in Program,Program-Verify, and Read operations. The HiNAND circuit includes amatrix of NAND memory cells divided to J Groups in column-directionhaving N global bit lines (GBLs). Each Group is divided to L Segments inthe column-direction and each Segment is further divided to K Blocks inthe column-direction. Each Block includes N Strings in thecolumn-direction or M Pages in row-direction and each String includes MNAND memory cells connected in series sandwiched by a top String-selecttransistor and a bottom String-select transistor. Each NAND memory cellin a Page is associated with a word line (WL). Here J, L, K, M, and Nare integer numbers and J is at least greater than 10. The HiNANDcircuit includes a BL-hierarchical structure comprising N metal3 linescorresponding to N metal2 lines and further to N metal1 lines all beingparallel to each other along the column-direction. Each metal3 line isused as one the N GBLs across all J Groups of NAND memory cells, eachmetal2 line is used as one of N sub-BL lines (SBLs) associated with eachcolumn of NAND memory cells across all Segments in each Group, and eachmetal1 line is used as one of N sub-sub-BL lines (BBLs) across allBlocks in each Segment. The HiNAND circuit also includes a plurality ofmetal0 lines laid out along the row-direction. The plurality of metal0lines includes at least one common source line connected to the NStrings of NAND memory cells in one or more Blocks of one or moreSegments of each Group, a first power/Vss line for all J Groups, asecond power/Vss line for all L Segments in a Group, and a thirdpower/Vss line for all K Blocks in a pair of Segments in one Group.Additionally, the HiNAND circuit includes N first GBL-select transistorscommonly controlled by a first gate signal to respectively couple the NGBLs with the first power/Vss line, N second GBL-select transistorscommonly controlled by a second gate signal to respectively couple the NGBLs with the corresponding N SBLs, N first SBL-select transistorscommonly controlled by a third gate signal to respectively couple the NSBLs with the second power/Vss line, N second SBL-select transistorscommonly controlled by a fourth gate signal to respectively couple the NSBLs with the corresponding N BBLs, and N BBL-select transistorscommonly controlled by a fifth gate signal to respectively couple the NBBLs with the third power/Vss line. Moreover, the HiNAND circuitincludes a Page Buffer circuit respectively coupled to the N GBLs andconfigured to store and supply multiple page data in the form ofsequential pipe-line. The BL-hierarchical structure in accordance with apreferred set of bias voltage conditions associated with at least thefirst gate signal, the second gate signal, the third gate signal, thefourth gate signal, and the fifth gate signal is configured to allowtemporary storages of program voltage and program-inhibit voltage in themultiple BBLs in one or more Segments of one or more Groups forperforming multiple-WL and All-BL Program, Program-Verify, and Readoperations simultaneously with less power and disturbance.

In another embodiment, the present invention provide a method ofperforming simultaneous multiple-WL and All-BL Program operation in aHiNAND memory array with BL-hierarchical structure. The method includesproviding the HiNAND memory array with BL-hierarchical structure asdescribed above. Additionally, the method includes pre-discharging all NGBLs, N SBLs, and N BBLs to Vss=0V. The method further includesprecharging the N BBLs in multiple selected Blocks of multiple selectedSegments of one or more selected Groups concurrently to a MV voltagefrom the corresponding third power/Vss line and latching the MV voltageinto a parasitic capacitance associated with each of the N BBLs. The MVvoltage being substantially same as a program-inhibit voltage of ˜7V.Furthermore, the method includes converting a page data having Vdd orVss levels on all the N GBLs from the Page Buffer circuit for oneselected page in each selected Block to a local data pattern in MV orVss levels respectively on parasitic capacitances associated with the NBBLs and holding the local data pattern in MV or Vss levels respectivelyon each parasitic capacitance associated with the N BBLs. The methodfurther includes performing Program operation independently on oneselected page in the selected Block in accordance with the local datapattern by ramping a program voltage applied to the corresponding WL toVpgm of about 20V. Moreover, the method includes performing Programoperation on multiple pages concurrently in accordance with respectivemultiple local data patterns preset sequentially for respect multiplepages, the multiple pages belonging to different selected Blocks of theone or more Segments of the one or more selected Groups.

In an alternative embodiment, the present invention provides a method ofperforming multiple-WL & All-BL Read and Program-Verify operations in aHiNAND memory array with BL-hierarchical structure. The method includesproviding the HiNAND memory array with BL-hierarchical structure asdescribed above. Additionally, the method includes first pre-dischargingN GBLs, N SBLs and N BBLs to Vss=0V and precharging the N BBLs and the NSBLs in one or more selected Groups to a pre-charge voltage ranging fromVdd to 7V. The method further includes discharging part of the N BBLsand the N SBLs to 0V in accordance with a page data stored in a selectedpage of NAND memory cells. Furthermore, the method includes sharing thepre-charge voltage in the remaining part of the N BBLs and the N SBLswith the corresponding GBLs to generate a reduced GBL voltage. Themethod further includes multiplying the reduced GBL voltage to be sensedby a latch sense amplifier to latch the corresponding page data to thePage Buffer circuit for storing as digital bits.

The present invention also provides a flow control for a simultaneouslyProgram, Program-Verify, and Read operations. The definition ofsimultaneously Read operation means the charge and discharge ofNAND-String in multiple Blocks in differ Groups are performed on thesame time. The read data from the selected Blocks is dumped to PB one byone. But due to the dump data from a selected page into PB is muchfaster than the time used for discharging the selected BBLs lines inaccordance with the stored page buffer, the operation of multiple-WL andAll-WL Read and Program is like simultaneous Read.

4. BRIEF DESCRIPTION OF THE DRAWINGS

The following diagrams are merely examples, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize many other variations, modifications, and alternatives.It is also understood that the examples and embodiments described hereinare for illustrative purposes only and that various modifications orchanges in light thereof will be suggested to persons skilled in the artand are to be included within the spirit and purview of this process andscope of the appended claims.

FIG. 1 shows a typical NAND array with one portion of Block and oneSense Amplifier (SA) shared by one paired NAND Strings including one OddString with its drain node coupled to BLo metal bit line and one EvenString with its drain node coupled to another BLe metal line.

FIG. 2 shows some typical time lines of some key control signals forproperly operating prior-art NAND array as seen in FIG. 1.

FIG. 3A shows a cross-sectional view of a 2-poly, NMOS, HiNAND memorycell with Program-Inhibit bias condition according to an embodiment ofthe present invention. The 2-poly, NMOS, HiNAND memory cell is formedinside a Triple P-Well within a Deep N-Well on top of a P-substrate.This HiNAND cell is preferably using non-Self-Boosting Program-Inhibitscheme to prevent the FN-channel tunneling Program, unlike traditionalSelf-Boosting (SB) technique commonly used in prior-art NAND.

The HiNAND cell's preferred non-SB Program-Inhibit bias voltageconditions are summarized below. No Program operation happens, thus NANDcell's Vt<−0.7V at an erased state.

a) Vg=Vpgm=15V-25V

b) Vs=Vd=MV≧7V

c) V_(TPW)=0V

d) V_(DNW)=Vdd

e) Vp-sub=0V

FIG. 3B shows preferred Program bias conditions according to anembodiment of the present invention. After Program, NAND cell's Vt isincreased from erased-state Vt to program states such as 3 A, B, Cstates with positive Vt for one MLC cell or 7 positive Vt states for oneTLC cell and 15 positive Vt states for one XLC cell.

a) Vg=Vpgm=15V-25V

b) Vs=Vd=0V

c) V_(TPW)=0V

d) V_(DNW)=Vdd

e) Vp-sub=0V

FIG. 3C shows eight regular Vt distributions of one TLC HiNAND cell witheight binary state assignments of 111, 110, 101, 100, 011, 010, 001 and000 for respective E, A, B, C, D, F, G and H states from left to rightaccording to an embodiment of the present invention. Many other 8 TLCstate assignments can also be accepted for this HiNAND cell and array.

FIG. 3D shows a preferred HiNAND3 array with 3-level BL-hierarchicalstructure according to a specific embodiment of the present invention.The HiNAND3 array preferably comprises J HiNAND Groups such as Group 1to Group J. Each HiNAND Group further preferably comprises L HiNANDSegments such as Segment 1 to Segment L. Furthermore, each HiNANDSegment preferably comprises K NAND Blocks such as Block 1 to Block K.Each HiNAND Block further comprises a plurality of regular NAND Strings.Each NAND String comprises N NAND cells connected in series with one topString-select transistor MS and one bottom String-select transistor MG.

All J NAND Groups comprise N long and heavy GBL metal3 lines such asGBL[1] to GBL[N] laid in parallel to each other in Y-direction andcoupled directly to N outputs of a top circuit block comprising of PageBuffer (PB), Multiplier, and Sense Amplifier (SA). Each GBL metal3 lineis further divided into J SBL metal2 lines (in other words, for theHiNAND array with total J Groups, each Group is divided into LSegments), for example SBL_1[1] through SBL_1[N] for Segment 1. EachSBL_L[N] is also laid in the Y-direction from Segment1 to Segment Lwithin each HiNAND Group. Each SBL metal2 line is further divided into KBBL metal1 line such as BBL_1_1[1] to BBL_1_K[1] also laid in theY-direction within the HiNAND Segment 1. In addition, each GBL, SBL andBBL line is respectively associated with one NMOS device connected to acorresponding power line such as GBLps, SBLps and BBLps, laid inX-direction (perpendicular to the Y-direction). These NMOS devicesinclude MGBLs, MSBLs and MBBLs. Each GBL, SBL, and BBL line also isassociated with another NMOS device connected between BLs in differentlevels. These devices include MGBLp and MSBLp.

FIG. 4 shows preferred circuits of one Multiplier, one Latch-SA and oneConnector circuit inserted in between the Multiplier and the Latch-SAcircuit per GBL according to an embodiment the present invention. Unlikethe conventional NAND scheme, each GBL of the present invention is notdirectly connected to the Latch-SA. Instead, each GBL is connected toits associated Multiplier first via one dedicated 20V NMOS device withits gate tied to a BIAS signal and its source coupled to a BLP signal.The output of the Connector circuit is coupled to one input of theLatch-SA with another input connected to a reference VREF signal.

FIG. 5 shows a table that contains a preferred set of bias voltageconditions for a preferred Multiple-WL & All-BL Read operation for thepreferred HiNAND array according to embodiments of the presentinvention. Each WL or Page of this preferred Multiple-WL Read operationuses an All-BL Read scheme to achieve less WL disturbance, less latencyand lower power-consumption. Thereby, a longer Read endurance cycle isaccomplished.

FIG. 6 shows a table that contains a preferred set of bias voltageconditions for a preferred Multiple-WL & All-BL Program andProgram-Inhibit operations for the preferred HiNAND array according toembodiments of the present invention to achieve less WL disturbance,less latency and lower power-consumption. Thereby, a longer Programendurance cycle is accomplished.

FIG. 7 shows a table that contains a preferred set of bias voltagecondition for one selected WL and unselected WLs for the preferredMultiple-WL and All-BL Program and Program-Inhibit operations accordingto embodiments of the present invention without using any Self-BoostingProgram Inhibit schemes for superior Program and Program-Inhibitoperations with longer P/E endurance cycles.

5. DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a more thorough understanding of the presentinvention. The detailed description of the present invention, referenceis made towards the accompanying drawings, flows and tables that form apart hereof and in which is shown, by way of illustration, specificembodiments in which the invention may be practiced. In the drawings,like numbers describe substantially similar components throughout theseveral views and embodiments. These embodiments are described insufficient detail with a goal to enable those skilled in the art topractice the invention. Other embodiments may be made without departingfrom the scope of the present invention. The following detaileddescription is not to be taken in a limiting sense, and the scope of thepresent invention is defined only by the appended claims and equivalentsthereof. In other instances, well-known structures and devices are shownin block diagram form, rather than in detail, in order to avoidobscuring the present invention.

Please note, if used, the labels left, right, top, bottom, middle,higher or lower level X or Y-direction, column or row direction,horizontal or vertical direction, have been used for conveniencepurposes only and are not intended to imply any particular fixeddirection. Numerical denotation using J, L, K, M, N, m, n, is also forconvenience purpose and corresponding examples of these numbers, such as1, 2, 3, 8, 16, 32, 64, 256, etc are not intended to limit the scope ofthe present invention defined by the appended claims. Instead, they areused to reflect relative locations and/or directions between variousportions of a circuit object or schematic diagram.

Unlike conventional NAND having only one-level metal bit line (BL)architecture, in general, the HiNAND array of the present inventionincludes a novel NAND cell array including a multiple-BL metal linehierarchical structure with at least 2 levels. Each local BL metal linein one level is preferably connected to one pull-up NMOS dividedBL-select device and one pull-down NMOS device which couples to a commonSL (sourceline). Each pull-up NMOS divided BL-select device is used asbridge to connect the BL metal line on top level to the BL metal line onbottom level. For example, 3-level BL-hierarchical metal lines in aHiNAND3 array will be explained with reference to FIG. 3D. Three levelsof the BL hierarchical structures mean that the top global BL (GBL)layer uses metal3 line, the middle Segment BL (SBL) layer uses metal2line located at 1-level lower than the top GBL metal3 line, and lastlythe Block BL (BBL) level uses metal1 line laid at 2-level lower than thetop GBL metal3 line but at 1-level lower than the middle SBL metal2line. Note, HiNAND3 stands for a HiNAND array with a 3-levelBL-hierarchy in the present invention. Similarly, HiNAND2 stands for aHiNAND array with a 2-level BL-hierarchy in the present invention. Theconventional NAND is like HiNAND1 with just one-level BL-hierarchy inthe present invention. Note, all GBLs, SBLs, and BBLs are using metal0layer for connecting corresponding common source line in X-directionacross the whole HiNAND plane and array.

For a HiNAND3 array architecture, from electric circuit viewpoint, eachcolumn of GBL of HiNAND3 array is preferably divided into 3 levels ofdivided BLs. In particular, the HiNAND array is divided into J Groups.Each Group is then further divided into L Segments. Lastly, each Segmentis further divided into K Blocks arranged in Y-direction. Similar as theconventional NAND, each column of the HiNAND Block comprises a NANDString having M NAND cells connected in series which is sandwiched by atop String-select NMOS transistor and a bottom String-select NMOStransistor. The values of M can be 16, 32, 64, 128 or any otherarbitrary integer number.

Unlike the conventional NAND with only 1-level BL decoder, a 3-level BLdecoder including a top Group-decoder, a middle Segment-decoder and abottom Block-decoder is required in the HiNAND3 array of the presentinvention. Similarly, a 2-level BL decoder including a Segment-decoderand a Block-decoder is required for the HiNAND2 array of the presentinvention. Now the operations and associated devices of each BL metallayer are explained below in accordance with the HiNAND array circuitshown in FIG. 3D.

Referring FIG. 3D, in a HiNAND3 array, each GBL is connected to one NMOSdevice, MGBLs, with two purposes from circuit viewpoint as explainedbelow.

-   -   1) GBL: Global Bit Line. The GBL has largest BL capacitance,        C_(GBL), laid out over the corresponding SBL (Segment Bit Line).        -   a) This is the top metal3 line that is used to connect J            NAND Groups in Y-direction within 2λ x-pitch. The length of            this metal3 GBL extends from HiNAND3 array top to the            HiNAND3 array bottom. This is the longest metal BL in            HiNAND3 array, laying in the Y-direction and is            perpendicular to WLs in X-direction.        -   b) MGBLs: This NMOS device has to sustain a V_(Inhibit)            voltage as a String-select transistor. The drain node of            MGBLs is connected to each GBL in the Y-direction. The            source node of MGBLs is connected to one corresponding GBLps            in the X-direction perpendicular to the Y-direction.        -   c) The GBLps line uses metal0 line. If GBLps=Vss, then it is            used as a Vss source line. If GBLps equals a VH voltage,            then it is used as Power SL line. The VH voltage is either            Vdd or greater than Vdd.        -   d) In other words, only one MGBLs device per one GBL metal3            line.    -   2) SBL: Segment Bit Line. The SBL has second largest BL        capacitance, C_(SBL). C_(SBL)≦ 1/10 of C_(GBL), assuming HiNAND        array is divided into J=10 Groups. The exact capacitance ratio,        Cr1=C_(SBL)/C_(GBL) is flexible, depending on the area and        power-consumption tradeoff of the preferred value of the        BL-charge sharing between C_(SBL) and C_(GBL).        -   a) This is the middle metal2 BL that is used to connect the            L HiNAND3 Segments in the Y-direction within 2λ x-pitch. The            length of this SBL metal2 line within each HiNAND Group            extends from the Group top to the Group bottom. This is the            second longest metal BL in HiNAND3 array, laying out in the            Y-direction and is also perpendicular to WLs.        -   b) MSBLp: This NMOS device also has to sustain a V_(Inhibit)            voltage as the String-select transistor. The drain node of            MSBLp is connected to each corresponding GBL. The source            node of MSBLp is connected to one corresponding SBL metal2            line.        -   c) MSBLs: This NMOS device also has to sustain a V_(Inhibit)            voltage as the String-select transistor. The source node of            MSBLs is connected to each corresponding metal0 line, SBLps.            The drain node of MSBLs is connected to the corresponding            SBL metal2 line.        -   d) The SBLps line uses metal0 line. If SBLps=Vss, then it is            used as a Vss SL line. If SBLps equals a VH voltage, then it            is used as Power SL line. The VH voltage is either Vdd or            greater than Vdd.        -   e) In other words, only one MSBLs and one MSBLp devices per            one SBL metal2 line.    -   3) BBL: Block Bit Line. The BBL has the smallest BL capacitance,        C_(BBL). Typically, C_(BBL)< 1/10 of C_(SBL), assuming each        Segment is divided into 10 Blocks. The exact capacitance ratio,        Cr2=C_(BBL)/C_(SBL) is flexible, depending on the area and        power-consumption tradeoff of the preferred value of the        BL-charge sharing between C_(SBL) and C_(BBL).        -   a) This is the bottom metal1 BL that is used to connect the            K HiNAND3 Blocks in the Y-direction within 2λ x-pitch. The            length of this metal1 BBL within each Segment extends from            the HiNAND3 Segment top to the HiNAND3 Segment bottom. This            is the shortest metal BL in the HiNAND3 array, laying out in            the Y-direction and is also perpendicular to WLs.        -   b) MBBLp: This NMOS device also has to sustain V_(Inhibit)            voltage as the String-select transistor. The drain node of            MBBLp is connected to each corresponding vertical SBL metal2            line. The source node of MBBLp is connected to one            corresponding BBL metal1 line.        -   c) MBBLs: This NMOS device also has to sustain V_(Inhibit)            voltage as the String-select transistor. The source node of            MBBLs is connected to each corresponding metal0 line, BBLps            (which can be mirrorly shared by two neighboring Segments).            The drain node of MSBLs is connected to the corresponding            BBL metal1 line.        -   d) The BBLps line uses metal0 line. If BBLps=Vss, then it is            used as a Vss SL line. If BBLps equals a VH voltage, then it            is used as Power SL line. The VH voltage is either Vdd or            greater than Vdd.        -   e) In other words, only one MBBLp device and one MBBLs            device per one BBL metal1 line.

For a HiNAND2 array architecture of the present invention, there areonly 2-level BL, thus only two metal lines of metal2 and metal1 are usedwithout using any metal3 line as seen in HinAND3 array. In the HiNAND2array, the NAND Group is not needed. The metal2 line becomes GBL andmetal1 line becomes SBL. In other words, SBL is upgraded to GBL, whilethe BBL is upgraded into SBL. The corresponding NMOS devices MSBL andMBBL assignments are the same as HiNAND3. Therefore, the detaileddescription would be skipped here for simplicity for those skilled inNAND architecture.

Now, the reason why the new HiNAND proposes to use tight multiple-metalBL lines than NAND's 1-metal BL will be explained below. From theconventional NAND design wisdom, requirements of multiple tight metal BLlines in HiNAND array of the present invention will increase NANDmanufacturing process steps and the die cost. Therefore, in past 25years, the 1-metal BL scheme in NAND array prevailed and has become thethumb of rule of design in NAND since its first product debut in 1988.But NAND density so far has been increased from the initial 1 Mb in 1988to 256 Gb in 2013. In other words, the NAND density has been increasedby about 1 million-fold. In next 10 years, the NAND density will bepotentially increased beyond 1 Tb or even beyond 10 Tb per die by usinga new 3D NAND flash technology.

In a conventional 1-level metal BL NAND array, the fastest Programoperation can only be executed at most in unit of one physical WL orpage in 1-cycle at a time. But today, when NAND technology feature sizemigrates toward below 2×nm, one physical WL program is even beingdivided into a slower but safer 2-cycle Odd/Even logic WL program due tosevere proximity-effect of coupling noise between BL-BL and WL-WL. Evenfor NAND Read operation ALL-BL 1-cycle faster Read has appeared in someNAND flash designs, the Odd/Even 2-cycle slower Read is still being usedin most NAND design for safe data quality.

Although the NAND design scheme is shifting from 2-cycle Odd/Even to1-cycle ALL-BL faster Read and Program operations, the 1-cycle accessspeed is still not fast enough to be in line with the million-fold orthousand-fold density increase in NAND flash memory.

In other words, the 25-year conventional NAND design, a need of dramaticread and program speed improvements to accommodate for the NAND memoryincrease is urgently needed. The present invention shows that unless theconventional NAND one-WL in one Block Program scheme can be replaced bymultiple-WL Program in different Blocks, otherwise, the Program speedhas hit a wall for NAND, regardless of 2D or 3D architectures.

Similarly, to dramatically increase the speed of the conventional 1-WLRead scheme in the conventional NAND, a method of multiple-WL Read inmultiple Segments is the key solution. As disclosed throughout thespecification, we discovered the bottleneck to using multiple-WL Readand Program, which is because the conventional NAND uses only one-levelmetal BL. The one-level metal BL is shared by all Strings in all Blocksin a column of the NAND array. The plurality of all one-level metal GBLsis coupled to a top Page Buffer (PB) that stores the incoming data to bewritten into the NAND cells in the selected page or WL of the selectedBlock.

In ALL-BL Program, all GBL voltages are coupled to the outputs of PB. Ifthe data of corresponding bits of PB is “0”, then the corresponding GBLsare coupled to Vss for Program operation and the cells' Vt would beincreased from initial erased E state with a negative-Vt value into thepositive-Vt value of programmed states such as A, B and C states. If thedata bit of PB is “1”, then the corresponding GBLs are coupled with Vddfor Program-Inhibit operation. A typical SLC Program time takes about 20μS. During this 20 μS page program time, all GBLs are filled with eitherVss or Vdd dedicated for NAND cells of one selected WL or page. To writeanother page, the GBLs' voltages will be filled with another datapattern of Vss and Vdd. Every page of data is different in GBL so thattwo or more data patterns cannot be sent to same GBLs simultaneously formultiple Program operations.

In other words, multiple-Program bottleneck is not due to the lack ofmultiple-WL selection in different Blocks but due to the inexcusablemultiple data patterns coupled to single GBL metal lines becauseexisting one-level GBL can only take one data pattern at a time withouthaving data contention in GBLs. The WL is not an issue, why? Accordingto today's NAND Program operation, the page program sequence starts fromWL[1] at the bottom page and ends at the last page or WL on the top ofthe NAND String.

Therefore, for multiple WL Program in different Block, multiple WLs inthe same location of the same selected page of the same selected Blockcan be programmed simultaneously with N-fold faster program time if NWLs in N different Blocks of HiNAND are selected for simultaneousprogram. Since the selected WLs are in the same locations of theselected string of the selected Block, thus the current Block decodercircuit does not need modifications but let each latch of each Blockdecoder be flexibly set or reset. That means the best case is to allowthe each latch of each Block decoder be flexibly set and reset so thatthe multiple set and reset can be easily implemented in multiple Blockdecoders to allow multiple simultaneous program. In this way, allselected WLs of the selected Blocks are directly accessed by the centralString-select decoders.

If the NAND String contains 32-WLs without dummy WLs, then the addresscombinational logic and voltages of total 32 WLs and 2 String-selectlines are directly provided from Central Block decoders. The one Vpgm(15V-25V) and 31 Vpass (8-10V) of HV and Vdd or Vss of two Stringcontrol signals are generated and controlled by this central Blockdecoder. The program timing and waveforms are same as the conventionalNAND with one Block select control only by the on-chip State-machinecircuit.

In summary, the desired multiple Program operation requires multipleselections of 32 WLs and 2 String-select lines in same logic and voltagecontrolled by the on-chip State-machine. With all Block decoder'slatches being preferably changed to allow the multiple set and reset,then the implementation of multiple selections of 32 WLs plus 2String-select signals with same voltages can be easily set up as theconventional NAND's State-machine circuit without change.

Now, the only issue left to solve for achieving multiple simultaneousprograms on multiple Blocks of HiNAND is how to provide the multipleunique (different) Program voltage (Vss) and Program-Inhibit voltage ofV_(Inhibit) to corresponding GBLs determined by the LV PB in HiNANDarray. In a first embodiment, the V_(Inhibit)≧7V and in a secondembodiment V_(Inhibit)=Vdd.

Note, in order to save the program power-consumption, the firstembodiment of V_(Inhibit)≧7V cannot be generated and coupled to thetargeted multiple SBLs or BBLs from the top LV PB because theconventional LV GBL-PB with latches cannot generate a HV of 7V. Even theLV GBL-PB is changed to a HV GBL-PB, the 7V coupled to long and big GBLtakes too much power consumption and it is against the green-memorydesign spirit because total GBL capacitance value for 256 Gb NAND canreach up to M×nF, where M>100 easily. In this new HiNAND array, the HV7V V_(Inhibit) voltage is supplied from the selected single BBLs. Sincethe capacitance of BBL is much smaller than the capacitance of GBL, thusthe power consumption of V_(Inhibit)≧7V to the selected BBL metal linescan be dramatically reduced by more than 100-fold. Of course, there canbe many variations, alternatives, and modifications. The detailedexplanation will be described in subsequent pages of this application.

Obviously, the conventional architecture of 1-level metal line GBL withlatches along with only one LV PB is not implementable to allow multipleunique or different page data with the program voltages of Vss andV_(Inhibit) voltage of Vdd being sent to the multiple destinations ofthe selected NAND cells' channels on the selected WLs in the multipleselected Strings of the multiple selected Blocks in the conventionalNAND array.

The present HiNAND inventions solve the above problems by adding 1 or 2divided BL metal line capacitances to form a 2-level or 3-levelBL-hierarchical architecture associated with themultiple-BL-program-voltage-trapping scheme without adding any locallatches acting as local pseudo page buffer in BBLs or SBLs, etc.

In an embodiment, a NAND array with a 2-level BL-hierarchical structurewith one extra metal2 line for BBL under metal1 line is referred as aHiNAND2 array of the present invention. In another embodiment, a NANDarray with a 3-level BL-hierarchical structure with one extra metal2line for BBL-cap (BBL capacitance) and metal1 line for SBL-cap isreferred as HiNAND3 array of the present invention.

There are several factors that determine which NAND array, HiNAND2 orHiNAND3, will be the best choice for the multiple-WL Program? For thepresent invention, the following factors including page Read, pageVerification (Program and Erase), Program, Erase and Read endurancecycles, power-consumption and Read latency are taken into considerationto select HiNAND2 or HiNAND3, as shown in the following Table I.

TABLE I Selection HiNAND2 HiNNAD3 comments Multiple WL Program only YesNo 2-level BL HiNAND2 array m2 for GBL m1 for SBL Multiple WL Program &No Yes 3-level BL HiNAND3 array Multiple Read m3 for GBL m2 for SBL m1for BBL Self-boosting & large Yes Yes Vpass-WL disturbance NoSelf-boosting & near zero Yes Yes Conventional NAND uses Vpass-WLdisturbance on unreliable SB, LSB and A, B, C program cells EASBProgram-Inhibit methods All-BL multiple Program Yes Yes All-BL multipleRead Yes Yes Which BL cap used for local BBL metal1 BBL metal2 For leastV_(Inhibit) charges PB for multiple-WL Program? Which BL cap used forBBL metal1 SBL metal2 For optimal charge-sharing Read optimalmultiple-WL Read?

As will be explained and fully understood later, the HiNAND2 array caneffectively achieve the same delivery of the desired multiple uniquepage data from single PB through single GBL metal2 buses to the targetedSBLs metal1 capacitance so that the page data pattern voltages the Vssand V_(Inhibit) voltages can be effectively latched at there for a longperiod of 200 μs program time as if it were from PB. In other words, thelocal large capacitance of SBLs metal1 line acts as a local SBL-PBwithout a real latch-circuit for storing the temporary page data that iscoupled from GBL-PB.

The traditional NAND's LV PB with a plurality of latches can be used forthe HiNAND2 array that act as a role of central LV GBL-PB with latchesto store and provide all multiple page data in the form pipe-linetemporarily. In other words, this LV GBL-PB with latches is designedintentionally to store only one page data to save silicon area.Definitely, more than one page data latches can be built in this LVGBL-PB circuit for easily pipe-line storage handling to save the download time from external I/Os to this LV GBL-PB and sequential page-dataloading time from LV GBL-PB to multiple targeted SBL-PBs in differentmultiple Blocks without any latches but SBL capacitance. Note, thedefinition of LV PB means all latch devices can use LV PMOS and NMOSdevice except only one connected to GBL used as a HV/LV isolation devicethat needs to be a 20V thicker-gate voltage for preventing 20V from thetriple-Pwell of NAND cell array during Erase operation.

For a HiNAND3 array, there are 2-level BL lines such as metal2 SBLs andthen metal1 BBLs. Thus, the lowest of metal1 BBL capacitance, BBL-cap,will replace the middle metal2 SBL capacitance, SBL-cap, as a local PBwithout any latches to store the page data for multiple-WL or pageProgram. This is referred as a local pseudo BBL page buffer withoutlatches.

As explained above, the order of BL capacitances among these GBL-cap,SBL-cap, and BBL-cap is defined as below due to the top metal BL layeris always much longer than the BL metal line laid one layer below, thushaving higher parasitic metal capacitance including fringe couplingcapacitance between two adjacent BLs. The order of values of BLcapacitances is: GBLcap>>SBLcap>>BBLcap.

The number of BBL pseudo page buffer can be determined by the tradeoffof HiNAND array size and the V_(Inhibit) charge current of each BBLpseudo page buffer. Note, the above so-called pseudo page buffer doesnot contain any latches as typical GBL-PB but only capacitance forstoring one temporary page data during multiple-page Program operationof the presentation. Also note, the number of required latches per NANDcell of GBL-PB is determined by the desired storage type of NAND cell.For a conventional NAND storage scheme, one latch is minimally requiredper SLC NAND cell and two latches per one MLC NAND cell, three latchesper one TLC cell and four latches per one XLC cell. For a 256-levelanalog storage, then 8-latch per one analog NAND cell is required.

In theory, the number N of BBL pseudo page buffer allows N multiplepages to be simultaneously programmed associated with only one centralGBL-PB. Thus, the N-fold Program time reduction can be achieved. Thedetails of charge-trapping techniques would be explained subsequentlyagain with reference to FIG. 3D and flows of HiNAND3 array circuit.

The selected pages of multiple selected Blocks for simultaneousmultiple-WL Program operation with the same requirement of only oneshared GBL-PB. The multiple unique pages are supplied one-by-one fromone shared N-bit PB on different timing during the BL Program andProgram-Inhibit setup period.

Assuming total N-bit of 16 pages or WLs are selected for simultaneousProgram, then 16 page N-bit data has to be provided from this singleshared N-bit LV PB placed on HiNAND array top. Each N-bit page data areloaded serially into this one LV-PB from external I/O bus in unit ofbyte or word. But in order to save the sizes of one PB silicon area,only one page data is preferably designed to achieve the smallest andmost economic PB design for the HiNAND array of the present invention.Even it is an 1-page PB, the real silicon size of this PB is fullydetermined by the desired storage types and design techniques. Forexample, for today's NAND memory, there are more than four storage typessuch as SLC, MLC, TLC, XLC and analog types. In LV-PB, one latch is usedfor a SLC NAND cell, 2 latches for a MLC NAD cell, 3 latches for a TLCNAND cell, and 4 latches for an XLC NAND cell storage. Other morelatches per NAND cell may be used for other NAND storage functions.

For this HiNAND array of the present invention, one option is to use 4or more latches per GBL per NAND cell to cover all SLC, MLC, TLC and XLCstorages. Even the real HiNAND storage is not XLC, 4 latches per GBL canbe used to store 4 bits of page data for the preferred pipe-line Programand Read for less repeat down loading time of serial data from externalI/Os to this LV GBL-PB.

In summary, in order to achieve the multiple-WL and All-BL Program andRead operations, a preferred 2-level BL-hierarchical HiNAND2 array or3-level BL-hierarchical HINAND3 array are proposed to work along withone LV GBL-PB. The lowest BBL-cap is used as the local BBL pseudo pagebuffer without latches to temporarily store the Vss Program voltage andV_(Inhibit) Program-Inhibit voltage in BBL-cap.

If the V_(Inhibit) voltage=Vdd, Vpgm (BL)=Vss, then the BBL pseudo pagebuffer stores N-bit of page data with Vss and V_(Inhibit) voltagescoupled directly from the LV GBL-PB with latches. If the V_(Inhibit)voltage≧7V, Vpgm (BL)=Vss, then the all N BBLcaps are precharged withV_(Inhibit) voltage initially through one selected BBLps bus running inparallel to WLs for least power consumption. Then GBL-PB supplies theVss (“0”) and Vdd (“1”) of page data to all GBLs. All initiallyprecharged 7V BBL lines are then discharged to Vss or retained 7VV_(Inhibit) voltage through a NMOS device MBBLs with its gate tied toVdd only for next page Program operation.

The above said hierarchical structure of multiple metal-line pseudo pagebuffers such as BBL pseudo page buffer and SBL pseudo page buffer forsimultaneous multiple-WL, All-BL Program and Read operations is stillnot sufficient. A conventional sensing scheme and program-inhibitvoltage for Vpass also need to be changed along for HiNAND memory. Allthese changes are derived from the NAND device physics and basicoperating schemes of the fundamental Read and Program methods used in aconventional NAND array. All these preferred changes in NAND array, PB,and program-biased condition and no Self-Boosting Program-Inhibitmethods are aimed to dramatically reduce the current, disturb of bothRead and Program operations. Besides, the Read and Program speed can beimproved more than 10-fold and even 100-fold for this novel HiNAND flashmemory. For either NAND or HiNAND design, the major peripheral circuitsinclude the Page Buffer, WL-decoders, BL-decoders, SL-decoders andSegment decoders, sense amplifier, the high-voltage (HV) pump circuitsfor respective Read, Program, and Erase operations and the on-chipstate-machine that automatically controls the defined timings,waveforms, voltages and sequences of key operations such as Erase,Erase-Verify, Program, Program-Verify, and Read operations.

In order to illustrate many advantages of the present invention, adetailed operation of the conventional NAND will be explained furthervia FIG. 1 based on an exemplary circuit of NAND array and senseamplifier from June Lee et al., “A 90-nm CMOS 1.8-V 2-Gb NAND FlashMemory for Mass Storage Applications,” IEEE J Solid-State Circuits, vol.38, No. 11, November 2003, pp. 1934-1942. The NAND array only shows twoBLs that are divided into one paired lines of BLo in right and BLe inleft. The BLo stands for Odd BL, while BLe stands for Even BL. The wholeNAND array is being divided into two BL groups with equal number of BLssuch as all Odd BLs and all Even BLs. In the simplified version of NAND,FIG. 1 shows that each BLe line only one NAND String is connected to it.Similarly, in each BLo line, only another one NAND String is connectedto it. In real NAND design, each BLo line or BLe line has connected to aplurality of NAND strings.

In FIG. 1, each NAND String has 32 NAND cells, for example, MC1 o-MC32 oin BLo, MC1 e-MC32 e in BLe. The 32 NAND cells are connected in serieswith one top String-BL-select transistor such as MS1 coupled to BLe andMS2 coupled to BLo, with their gates tied to a common signal of SSL andone bottom String-SL-select transistor such as, MG1 and MG2, with theirgates tied to another common signal denoted as GSL and the String'ssource nodes are connected to a common SL, denoted as CSL. Note, allMS1, MS2, MG1 and MG2 transistors are a MHV NMOS 1-poly devices thatmust sustain the String Program-Inhibit voltage across their respectiveVds of around 7V during the self-boosting coupling effect commonly usedin NAND FN-tunneling page Program operation. The number of NANDtransistors in each NAND String can be 16, 64, 128 or any arbitraryinteger number. And the NAND storage types can be SLC, MLC, TLC, XLC oranalog, depending on the applications and data reliability requirements.Note, for mere convenience of explaining the differences of NAND andHiNAND arrays, here 32 T NAND String is used in FIG. 1 but although anyother integer numbers can be used without unduly limit the scope of theclaims.

In the following sections, explanations of key operations of theconventional NAND are referenced to both FIG. 1 and FIG. 2. These keyoperations include Program, Program-Verify, and Read operations.Particularly, the Read operation would be explained in more details. Inother words, for a regular NAND Read operation, the selected NAND cellsin a selected page are assumed being programmed already with differentVtn state before Read. This Vtn are defined differently in differentstorage types such as SLC, MLC, TLC, XLC or analogue storages. All thoseconventional Program and Erase schemes and methods can still be usedhere. But instead, because Program-Verify and Erase-Verify are like Readoperation, thus they can be replaced by the Read circuits and techniquesdisclosed here as for the purpose of reducing current, disturbance andlatency.

In FIG. 1, each NAND BL has added one 20V high voltage (HV) NMOS deviceas a HV buffer to protect each corresponding LV latch-type SA (senseamplifier) from being damaged during the 20V Erase operation. These HVNMOS devices are MN3 and MN1 for BLe and MN2 and MN4 for BLo. Sincethese 20V HV buffer devices have to sustain more than 20V Vdspunch-through and to fit in a very tight pitch of each BL in NAND arraysuch as 19 nm width made of 20 nm NAND node but the channel length ofthese devices are made more than 0.5 μm. As a result, these HV NMOStransistors are associated with a device width/channel ratio ˜25, thushave very high resistance and large silicon area and definitely are notgood for BL precharge operation during the first cycle of NAND Readoperation.

Referring to FIG. 1, the BL precharge current path is flowing from aPMOS device, MP20, through a common node of SO and split into two paths.FIG. 1 further shows that a first precharged current path is through MN3to precharge BLe with BLSHF signal coupled to a voltage higher thanMN3's Vt and the gates of MN1 and MN4 being grounded in a shut-offstate. Conversely, a second precharge current path is through MN4 withits gate coupled to similar BLSHF signal on MN3 into a conduction stateto precharge BLo's big capacitance with MN3 held in shut-off state bygrounding BLSHF signal.

Although, the gate voltage of both MN3 and MN4 can be increased to ahigher voltage during each BL precharge cycle to reduce the conductionresistance, the full passage of Vdd from node SO supplied by a PMOSdevice, MP1, results in many disadvantages. For example, all Odd andEven BLs, BLo and BLe, in prior-art NAND array would be pre-charged to ahighest value of Vdd for the initial V_(BL). That would result in thehighest BL pre-charge current and the slowest discharge speed, thus theslowest read latency and largest Read-induced WL-disturbance due to thelongest discharge time. All these disadvantages are against today'slow-power and low-disturbance green NAND design practice. Thus, it isdesired to reduce the charged V_(BL) voltages of BLe and BLo below Vddwith a value of around 0.9V for a reliable sensing margin as well ascurrent reduction.

During the precharge cycles in Read, Program-Verify, and Erase-Verifyoperations, the gate signal, PLOAD, of MP1 is grounded to fully turn onthe PMOS MP1 device. The node of SO would be precharged to Vdd value tofully turn on the gate of NMOS device, MN6, along with MN5 and MN7 NMOSdevices all in a shut-off state because the gates of MN5 and MN7 aregrounded. In order to limit the V_(BL)=0.9V at BLo and BLe with SO=Vdd,the gate voltage of 20V devices of MN3 and MN4 have to be clamped at avoltage, V_(BLSHF)=0.9V+Vt, where Vt is the threshold voltage of eitherMN3 or MN4. Traditionally, signal V_(BLSHF) is set to a value of 2.1V.That proves the Vt value being tuned to be 1.2V for both 20V NMOSenhancement devices MN3 and MN4.

In order to ensure the precharge current flow from MP1 to BLe withoutleakage, the 20V HV device MN4 along the current path has to be kept inshut-off high-impedance state with gate tied to ground as seen inFIG. 1. BLe is the selected BL in ½-BL Read in the NAND array.Conversely, for the non-select BLo, it is pulled to ground through MN2device with its gate coupled to Vdd voltage. If Vdd is 1.8V, MN2 gate of1.8V is still higher than its Vt of 1.2V, thus BLo is set to 0V. Thatmeans during the ½-BLs Read scheme, the half of non-selected BLs wouldnot endure the high BL precharge current but at expense of highWL-disturbance.

On the contrary, if BLo becomes the selected BL, then BLo=0.9V butBLe=0V as the un-selected BL. In some other conventional applications,the node between 0V HV devices of MN1 and MN2 are tied to Vdd. Thatmeans the V_(BL) of non-selected BLs are set to be Vdd, instead of Vss,for avoiding WL-disturbance by self-boosting effect as Program operationbut at expense of adding precharge high current in half of BLs. Thedetails can refer to many prior-art NAND designs.

In conclusion, the conventional NAND Read operation has the followingdrawbacks:

-   -   1) It is not an ALL-BL 1-cycle one full physical-page Read        scheme:        -   Thus the Read latency is 2-fold (2×) slower because reading            one whole physical page needs two cycles. The first cycle is            to read the Odd page and the second cycle is to read Even            page or vise versa.        -   a) It consumes averaged 1.5-fold (1.5×) BL precharge current            due to 2-cycle Read: It is due to when reading first ½-page            BLe lines, it still needs to precharge whole BLe lines and            whole BLo lines to avoid Read-induced WL stress happening on            the NAND flash cells in selected page in BLo lines. After            reading NAND cells in all BLe lines, all BLe lines may be            discharged to Vss if all cells stores the same Vt. Then,            when the second cycle moves to read all BLo lines, all BLe            lines still need to be pre-charged again but not BLo lines            because they are still in precharged state done in the first            cycle. As a result, total BLo and BLe being precharged 1.5×.        -   b) 2-cycle Read suffers 2-fold Read-induced Vpass (6V) WL            disturbance:            -   It is because each ½-page Read, all 32 WLs have to be                coupled with Vpass of 6V for 31 times during the whole                32T NAND string read course. Regardless BLo or BLe read,                2-cycle Read will suffer 2-fold stress, thus shorter                lifespan.        -   c) Precharge and discharge of BLo and BLe is too slow            because it has to go through 20V devices of MN3 and MN4.    -   2) It is not an All-BL physical-page Program scheme.    -   3) It cannot perform multiple-WL Program and Read operations.        Therefore, the Program and Read operation latency is getting        worse when NAND memory density is reaching above 256 Gb when        NAND technology migrates down to below 2×nm node.

Additionally, the function of the conventional NAND Latch SA and storagecircuit will be explained below in accordance with the waveforms andtime lines shown in FIG. 2. The Latch SA circuit is comprised of two LVCMOS Inverters INV1 and INV2. Before the precharge cycle, the Latch hasto be reset to high at node A by turning on the LV PMOS device MP2 withLV NMOS device MN7 biased in off-state by grounding PBLCH signal so thatno leakage path from node A to Vss through LV NMOS devices MN6 and MN7as seen in FIG. 1.

After precharge-cycle, if the selected NAND cell's Vt is higher than aRead/Verify voltage V_(RD), then there is no conduction current flowthough the selected NAND cell in the selected BLe. As a result, theinitial precharge voltage at SO still retains Vdd and the selected BLeretains 0.9V, e.g., SO=Vdd and BLe=0.9V. Thus when PBLCH signal switchesfrom Vss to Vdd, the node A will be pulled down to Vss to flip the Latchstate because both MN6 and MN7 are biased in a conduction state. The sumof the effective pull-down resistance of two LV NMOS devices, MN6 andMN7, is made smaller than the pull-up resistance of the PMOS device MP1.Conversely, if the selected NAND cell's Vt is smaller than V_(RD), thenthe NAND cell will conduct the current to pull down BLe's prechargevoltage of 0.9V to ground because MP1 is in off-state and cannot hold SOvoltage at Vdd again. As a result, the MN6 will be in shut-off statebecause its gate V_(SO)=0V. Therefore, node A still stays at Vdd andNAND cell Vt is detected to be higher than V_(RD). In SLC storage, onlyone V_(RD) value is used. In MLC storage, there are three V_(RD) valuesto be determined from three steps of three WL's voltages.

FIG. 2 shows the waveforms and time sequence for one Read operation:

-   -   a) t0-t1: The initial set up period        -   BLSHF signal is set to Vdd=1.8V to connect SO to BLe but            disconnect to BLo.        -   PBRST signal switches from Vss to Vdd to set node A to Vdd            and then shut off again.        -   PLOAD signal is set to Vdd to shut off MP20 and set SO to            Vss.        -   SO=Vss, BLe=Vss (Initial voltage).        -   PBLCH=Vss to prevent leakage through MN25 during Latch's            preset period.        -   Node A=Vdd after Latch preset period.        -   WL (selected) at Vss.        -   WLs (non-selected) at Vss.    -   b) t1-t2: BL precharge, WL-select set up and WL-non-select        charge-up period        -   BLSHF signal is set to Vdd=2.1V to precharge BLe=0.9V but            BLo=VSS.        -   PBRST remains at Vdd to keep node A=Vdd.        -   PLOAD is set to Vss to supply the precharge current to BLe            through MN23 with MN22=off state.        -   SO=Vdd, BLe=0.9V (Initial voltage), BLo=0V.        -   PBLCH=Vss to prevent leakage through MN25 during Latch's            preset period. Node A remains at Vdd.        -   WL (one selected) at V_(RD) switched from 0V to V_(RD),        -   WLs (31 non-selected) at V_(READ) switched from 0V to 6V.    -   c) t2-t3: BL discharged or remains precharged state, WL-select        set up and WL-non-select charge-up period        -   BLSHF signal is set to Vss to shut off MN23 for faster BLe            discharge due to no prechareg current flow again if cell's            Vt<V_(RD). If cell's Vt>V_(RD), then BLe stays at precharge            value of 0.9V.        -   PBRST remains at Vdd to keep node A at Vdd.        -   PLOAD is set to Vdd to stop the precharge current to BLe            through MN23 with MN22 at off state.        -   SO=Vdd and BLe=0.8V if NAND Vt>V_(RD) but SO=BLe=Vss if NAND            Vt<VRD PBLCH remains at Vss to prevent leakage through MN25            during Latch's preset period.        -   Node A remains at Vdd.        -   WL (selected) keeps V_(RD)=0V for SLC.        -   WLs (non-selected) keep pass voltage V_(READ)=6V.    -   d) t3-t4: NAND cell Vt sensing and determination period        -   BLSHF signal is set to 1.3V to reconnect SO to BLe,            preparing for sensing NAND cell in BLe.        -   PBRST remains at Vdd to keep node A at Vdd.        -   PLOAD is set to Vdd to stop the precharge current to BLe            through MN23 with MN22 at off state.        -   SO=Vdd and BLe=0.8V if NAND Vt>V_(RD) but SO=BLe=Vss if NAND            Vt<VRD PBLCH is one-shot pulse to latch the precise data            through MN25 during Latch's preset period.        -   Node A remains at Vdd.        -   WL (selected) keeps V_(RD)=0V for SLC.        -   WLs (non-selected) keep pass voltage V_(READ)=6V.    -   e) t4-t5: The end of ½-page Read operation:

All signals are reset with a set of biased conditions like at t0-t1,preparing for BLo sensing for next Read cycle.

FIG. 3A shows a cross-sectional cell configuration of one 2-poly, NMOS,HiNAND cell under Program-Inhibit bias condition according to anembodiment of the present invention, which is being formed inside theTPW, within the DNW on top of P-substrate. In a specific embodiment,this HiNAND cell is preferably using a non-Self-Boosting Program-Inhibitscheme to prevent the FN-channel tunneling Program. Self-Boosting (SB)technique is commonly used in typical NAND design.

The HiNAND cell's preferred non-SB Program-Inhibit V_(Inhibit) voltagebias conditions are summarized below. With the following bias conditionto the selected NAND cell in the selected WL or page of the selectedBlock, no Program operation happens. Thereby, the NAND cell's Vt stay atthe initial Erased state, Vte, e.g., Vte<−0.7V. As we know that in theconventional NAND Program operation, this V_(Inhibit) voltage is notsupplied directly from each corresponding data bit of the PB througheach corresponding GBL metal line. Instead, it is generated by SB(Self-Boosting scheme) from ramping a Vpgm voltage of one selected WL tothe channels of selected NAND cells. The selected cell's channel voltagestarts from the initial precharged floating voltage of Vdd-Vt. The Vddvoltage is supplied from each bit of PB through each corresponding GBL.But the coupling effect is strongly affected by the stored Vts of cellsin adjacent BLs and WLs. Thus the V_(Inhibit) voltage is also affectedby the background data patterns of adjacent cells and is gettingunreliable when NAND technology migrates to below 2×nm. Therefore, themost reliable way to have V_(Inhibit) voltage in the channels ofunselected programmed cells in the selected page is to directly couplewith a strong V_(Inhibit) HV power source generated from a dedicatedV_(Inhibit) charge-pump (driver) circuit. But this V_(Inhibit) voltageis preferably not being supplied from PB through all long GBL metallines. In today's NAND technology, each GBL capacitance may have a valueranging 3-5 pf. For an 18 KB GBL, the total GBL capacitance would reachup to 128 nF, which will consume too high current when all the GBLcapacitance is charged to V_(Inhibit) voltage in worst case.

In some alternative approaches, a V_(Inhibit) voltage of 7V is suppliedfrom a selected source line into the Flash channels on the selected WLof the selected NAND Blocks so that the power consumption can be reducedduring V_(Inhibit) precharge operation. But the current flow of thesupplying V_(Inhibit) voltage is through the NAND String bottom thatcontains many programmed cells with higher Vt values. That would makethe V_(Inhibit) charges to flow from NAND String bottom up to theselected NAND cells' channels more difficult unless the Vpass voltage isincreased more but that would induce more Vpass WL disturbance.Additionally, V_(Inhibit) charge flow will suffer more resistance topass through these programmed NAND cells in series from below WL of theselected program cells. This current flow of V_(Inhibit) HV from NANDString bottom is also against the current flow of the LV Vdd and Vssfrom NAND String top.

In a specific embodiment, this HiNAND BL-hierarchical structure isconfigured to supply V_(Inhibit) HV from a 7V power line through theselected bus BBLps by a V_(Inhibit) charge-pump (driver) circuit. EachBBLps is preferably driven by each corresponding driver circuit.Therefore, only one BBLps laid out in a horizontal (X-direction) lineperpendicular to the GBL metal line is selected to precharge theselected BBL line with a capacitance much smaller than the capacitanceof 18 KB long and heavy GBL line. Thus, lots of power consumption can besaved for this HiNAND Program-Inhibit scheme.

Since a low-power direct V_(Inhibit) precharge can be achieved in thepresent HiNAND design so that the unreliable SB method is replaced by apreferred non-SB Program-Inhibit (PI) scheme. Note, all conventional PIschemes including SB, LSB and EASB use self-boosting technique, thus areaffected by background NAND flash patterns and all are unreliable in thesame sense.

In an embodiment, the direct V_(Inhibit) precharge method implementedfor the present HiNAND array is to precharge all BBL lines in theselected Segment. Thus the V_(Inhibit) voltage would be coupled to GBLmetal3 lines through SBL metal2 lines. Those GBL metal lines as well asSBL metal lines being preset to Vss will discharge the corresponding BBLlines to Vss but those GBL lines and SBL lines being preset to Vdd-Vtwill retain those corresponding BBL lines at V_(Inhibit) voltage withoutbeing discharged. As a result, both program BBL voltage (Vss) andprogram-inhibit BBL V_(Inhibit) voltages will be selectively retained ascharges in a plurality of Block BBL capacitors BBLcaps. Each BBLcap hasa value ranging from 0.1 pf to 0.5 pf. Thus these local BBLcaps becomethe local voltage tanks of Vss and V_(Inhibit) with enough charges. Thedirect Vss and Vdd-Vt voltages supplied from PB through GBL and SBLlines become unnecessary during the Program period of 2000 per SLCProgram operation. Therefore, the local BBL selected transistors arethen shut off to release the SBL and GBL lines for next page data to besupplied for the next selected page in the different Blocks in thedifferent or same Segments of different or same Groups of the HiNANDarray. The Multiple-WL Program set up to trap the desired Vss andV_(Inhibit) voltages in accordance with the page data will be repeatedand stopped once all the desired N page data being fully loaded into theselected N BBL capacitors.

The following biased conditions are the preferred Program andProgram-Inhibit bias conditions of a HiNAND cell. Actually, each HiNANDcell is the same as a NAND cell. Thus, the single cell Program, Erase,and Read conditions can be kept the same as the conventional NAND. Boththe source node and the drain node of the selected HiNAND cell will beset to a MV=V_(Inhibit)≧7V as a program-inhibit voltage V_(Inhibit).

1) Program-Inhibit bias conditions for 2-poly HiNAND or NAND cell (seeFIG. 3A):

a) Gate Vg=Vpgm=15V-25V

b) Drain and Source Vd=Vs=MV=V_(Inhibit)≧7V

c) TPW V_(TPW)=0V

d) DNW V_(DNW)=Vdd

e) P-substrate Vp-sub=0V

After Program operation, these PI-cells would be prevented from beingprogrammed, thus the cell Vts would stay at the erased-state, Vte, whereVte≦−0.7V, typically.

2) Program bias conditions for 2-poly HINAND or NAND cell (see FIG. 3B):

a) Gate Vg=Vpgm=15V-25V

b) Drain and Source Vd=Vs=0V

c) TPW V_(TPW)=0V

d) DNW V_(DNW)=Vdd

e) P-substrate Vp-sub=0V

After Program operation, the HiNAND cell's Vt is increased fromerased-state value of a negative Vte to the programmed state values ofpositive Vts. For example, 3 MLC states A, B, C for one MLC cell, 7positive states for one TLC cell, and 15 positive states for one XLCcell.

In a specific implementation, FIG. 3C shows the regular 8Vt-distributions of one TLC HiNAND cell with 8 binary state assignmentsof 111, 110, 101, 100, 011, 010, 001 and 000 for eight respective statesof E, A, B, C, D, E, G with the reference voltages of R1-R7 andVFY1-VFY7 between each adjacent MLC states for a MLC Read operations.Many other 8 TLC state assignments can also be accepted for this HiNANDcell and array.

FIG. 3D shows a preferred HiNAND3 array with 3-level BL-hierarchicalstructure of the present invention. In each level of the BL-hierarchicalstructure there is one dedicated metal line, running in Y-direction witha different BL capacitance due to different length. In this HiNANDarray, the length of a top BL line is preferably laid out to be longerthan the length of each corresponding lower-level BL line, giving arelatively larger BL capacitance for the top BL line.

In a specific embodiment, the flash cell architecture of the HiNAND3array preferably comprises J HiNAND Groups such as Group 1 to Group Jlaid in the Y-direction as shown in FIG. 3D. Additionally, each HiNANDGroup preferably comprises L HiNAND Segments such as Segment 1 toSegment L also laid in the Y-direction. Furthermore, each HiNAND Segmentpreferably comprises K NAND Blocks such as Block 1 to Block K still laidin the Y-direction. Moreover, each HiNAND Block comprises N NAND Stringsaligned in X-direction (perpendicular to the Y-direction). Each NANDString in a Block (e.g., selected Block 1 within Segment 1) comprises MNAND cells, denoted as MCs, connected in series with one topString-drain Select NMOS transistor, denoted as MG, gated by GSL[1], andwith another bottom String-source Select NMOS transistor, denoted as MS,gated by SSL[1] signal. The desired value of M can be 8, 16, 32, 64, 128or any arbitrary integer number, without using dummy NAND cells. Thedetermination of the value of m is fully depending on the specs andapplications. For example, in a 2×nm NAND node, M=64 is very popularlyused because it is for an optimized NAND String length size andperformance.

Each Group comprises N global BLs (GBLs) such as GBL[1] to GBL[N] usingthe long and heavy top metal3 lines laid in parallel in the Y-directionand perpendicular to WLs or pages. These GBL metal3 lines are connecteddirectly to N outputs of a top circuit block comprising of Page Buffer(PB), Multiplier and Sense Amplifier (SA). Each of the N GBL metal3lines is further divided into J SBL (Segment BL) metal2 lines connectedin parallel to each GBL. The N SBL lines in one Segment, for example,SBL_1[1] to SBL_L[N] in Segment 1, are arranged in X-direction. EachSBL_L[N] line is still laid out in the Y-direction in parallel to eachGBL[N] metal3 line but having a preferred much shorter length. Each SBLmetal2 line is laid out across all L Segments from Segment1 to Segment Lwithin each HiNAND Group. Thus, a length of SBL, L_(SBL), is rangingfrom 1/20 to 1/10 of the length of GBL, L_(GBL).

The length ratio C_(SBL)/C_(GBL) being in an range from 1/20 to 1/10 isselected for achieving a fast All-BL Read operation in unit of one fullphysical page of this HiNAND array by using a DRAM-like BLcharge-sharing technique. It is know that the BL charge-sharing betweenDRAM cell's capacitance and DRAM BL capacitance is done by making asimilar ratio C_(cell)/C_(BL) in a range from 1/20 to 1/10. The detailedoperation of the preferred DRAM-like charge-sharing technique is shownbelow to apply to the All-BL Read operation associated with the HiNANDof the present invention.

In this HiNAND array (see FIG. 3D), the All-BL Read operation is just anAll-GBL Read operation. For conventional NAND, there are options ofall-BL Read and Odd/Even Read. Firstly, an All-BL Read operation can beexecuted like a 1-cycle Read from one full physical WL or page of NANDarray, though other approaches of All-BL sensing technique without aprecharged state can be used as well for one full physical WL or pageRead. The WLs and BLs bias conditions of the selected String in theselected Block are listed below:

-   -   a) Read voltage for a select WL=Vrm, m=1 for SLC Read but m=1,        2, 3 for MLC Read.    -   b) Vr1=0V for SLC Read to distinguish E state and A state.    -   c) Vr1=0V, Vr2=1V, and Vr3=2.5V for MLC Read, where Vr2 is used        distinguish A state and B state and Vr3 is used distinguish B        state and C state.    -   d) V_(GBL) of about 0.7V to 1.0V is precharged to all GBL lines        initially prior to reading.    -   e) V_(GBL) is about 0.7V to 1.0V, if the selected NAND cell's Vt        is above Vrm, thus no conduction of cell current.    -   f) V_(GBL) is 0V, if the selected NAND cell's Vt is below Vrm,        thus a conduction of cell current.

Secondly, in a conventional NAND an Odd/Even Read operation can beexecuted like a 2-cycle Read from one full physical WL or page of NANDarray, though other approach of All-BL sensing technique without aprecharged state can be used as well for one full physical WL or pageRead. The whole physical WL is divided into 2 halves. One half BLsbelong to the Odd-BL group denoted as BLo lines and the other half BLsbelong to the Even-BL group denoted as BLe lines as seen in FIG. 1. TheWLs and BLs bias conditions of the selected String in the selected Blockare listed below. The Read voltage, Vrm (m=1, 2, 3 . . . depending ontypes of storage like SLC, MLC . . . ), of one selected WL is kept thesame as the one for above All-BL Read operation.

-   -   a) Read voltage for a select WL is Vrm, m=1 for SLC Read but        m=1, 2, 3 for MLC Read.    -   b) Vr1=0V for SLC Read to distinguish E state and A state.    -   c) Vr1=0V, Vr2=1V, and Vr3=2.5V for MLC Read, where Vr2 is used        distinguish A state and B state and Vr3 is used distinguish B        state and C state.    -   d) V_(GBLo) is set to 0.7V-1.0V or 0V when GBLe lines are        selected for ½-WL Read.    -   e) V_(GBLe) is set to 0.7V-1.0V or 0V when GBLo lines are        selected for ½-WL Read.    -   f) V_(GBLo) is 0V, if the selected NAND cell's Vt in GBLo is        below Vrm, thus a conduction of cell current.    -   g) V_(GBLo) is 0.7V-1.0V, if the selected NAND cell's Vt in GBLo        is above Vrm, thus no conduction of cell current.    -   h) V_(GBLe) is 0V, if the selected NAND cell's Vt in GBLe is        below Vrm, thus a conduction of cell current.    -   i) V_(GBLe) is 0.7V-1.0V, if the selected NAND cell's Vt in GBLe        is above Vrm, thus no conduction of cell current.

Unlike the All-BL Read operation in conventional NAND, the All-GBL Readoperation in the HiNAND array of the present invention utilizes apreferred DRAM-like charge-sharing technique with details beingdisclosed below. In particular, one major difference of the All-GBL Readversus conventional All-BL Read is that a pre-Read step for prechargingAll-GBL lines to Vdd-Vt is not needed. Instead, All-GBL lines of theHiNAND array (see FIG. 3D) are pre-discharged to Vss through one 7V NMOSdevice MGBLs (which is a similar device as MSe and MSo in FIG. 1 of theconventional NAND array). Since the 7V NMOS device has thinner gateoxide layer than the 20V device MN3 and MN4 in the conventional NAND,thus the discharging and charging of GBL line is speeded by 5-fold.

In other words, in this HiNAND All-BL Read operation, no GBL isprecharged to Vdd-Vt. Thus power-consumption of GBL-precharge step istotally eliminated. A new set of WLs and BLs bias conditions of theHiNAND All-BL Read operation is listed below, referring to FIG. 3D:

-   -   a) Read voltage for a select WL=Vrm, where m=1 for SLC Read but        m=1, 2, 3 for MLC Read.    -   b) Vr1=0V for SLC Read to distinguish E state and A state.    -   c) Vr1=0V, Vr2=1V, and Vr3=2.5V for MLC Read, where Vr2 is used        to distinguish A state and B state and Vr3 is used to        distinguish B state and C state.    -   d) V_(GBL) is 0V for all GBL lines, regardless of data stored in        PB. This is done by coupling G_PRE to Vdd and GBLps to Vss so        that all GBLs are in a conduction state to pull down the voltage        of all GBL[N] to Vss, where the number N varies from 1 to N.

Note, this HiNAND All-BL Read operation does not require the long heavyglobal bit line to be precharged. Therefore, high power consumption dueto the big total capacitance of about 128 nF in all GBL metal3 lines iseliminated. Instead, the precharge is switched to divided shorter localbit lines with much smaller capacitances and a DRAM-like charge-sharingscheme along with the WL-voltage is used to provide a much reduced GBLcharge.

In a specific embodiment, the All-GBL HiNAND Read operation is performedusing a three-step process. In a first step of the All-GBL Readoperation, precharge of local BBL and SBL is performed. In particular,the preferred precharge operation happens on the shorter SBL metal2lines that have a length equal to only 1/20 or 1/10 of the length of thelong GBL, assuming that the HiNAND array is divided into J>10 Groups.Referring to FIG. 3D, these SBL lines include SBL_1[1] to SBL_1[N]. Theprecharged SBL voltage is Vdd=1.8V in a specific embodiment of thepresent invention. The following Table II summarizes the two types ofNAND precharge operation ((assuming total number of Groups is J=10 forthe HiNAND as an example, although typical choice of J is 8 or 16).

TABLE II HiNAND NAND Precharged voltage 1.8 V 0.9 V Prechargedcapacitance SBLcap = 1/10 of GBLcap GBLcap Precharged power ratio 0.2X1X With All-BL Read scheme Precharged power ratio 0.1X, All-GBL Readscheme 1X, Odd/Even Read scheme

As seen from above simple calculation in Table II, the HiNAND onlyconsumes about ⅕ power of prior-art NAND in Read operation when bothadopt the All-BL Read operation with precharge scheme. The HiNAND array(with 10 Groups) only consumes at least 1/10 power compared to aprior-art NAND array in Read operation when the HiNAND uses All-GBL Readscheme while the prior-art NAND uses Odd/Even Read scheme. For Odd/EvenRead scheme, the whole N GBL lines have to be additionally prechargedonce to Vdd-Vt besides the regular N GBLs precharges determined by thestored Data pattern (i.e., 0 or 1) in PB. For example, ½N×GBLo isprecharged to Vdd-Vt when reading ½N GBLe. Thus when reading ½N GBLe,total Charge1=½N×GBLo×0.9V+½N×GBLe×Data pattern. Similarly, when reading½N GBLo, total Charge2=½N×GBLe×0.9V+½N×GBLo×Data pattern. Thus, totalcharge in a 2-cycle Odd/Even whole page Read isCharge1+Charge2=N×GBL×0.9V+N×GBL×Data pattern. But total charge in a1-cycle HiNAND All-BL Read is N×GBL×Data pattern. The “Data pattern”means 0.9V for “1” data but Vss for “0” data.

When All-GBL Reading is performed for Group 1, all N SBL metal lines andN BBL metal lines are precharged to 1.8V. The operation is performedfrom SBLps[1] metal0 line through N 7V NMOS devices MSBLs to precharge NSBL lines and from BBLps_1[1] through N 7V NMOS devices MBBLs toprecharge N BBL lines with gates of N NMOS devices MGBLp coupled to Vssto prevent the leakage from SBL metal line to corresponding GBL metalline. The NMOS devices MGBLp and MSBLs (see FIG. 3D) are preferably madeby same String-select 1-poly transistors as conventional NAND, such asMG or MS in FIG. 1. The gate voltage of device MSBLs is S_PRE[1]selected to be Vdd+Vt to allow the full 1.8V passage from SBLps[1](metal0 line) to each of SBL_1[1] through SBL_1[N]. The device MSBLs hasto be formed within the same TPW and DNW with the HiNAND array. DuringHiNAND Erase operation when TPW=20V, the gate of the MSBLs device isfloating to cancel the 20V stress from TPW below.

A second step of the all-GBL HiNAND Read operation is associated with apage data development period. After all N SBL lines are being fullyprecharged to 1.8V or even a little higher such as 2.0V, a desired setof various control voltages of GSL, SSL and all WLs in one page isapplied with all MSBLp devices being set to an off-state to performAll-BL Read operation or Program-Verify operation to the selected WL ofthe selected NAND Block. For example, for a SLC Read, the selected WL isset to 0V, and 63 non-selected WLs (of a 64T String per Block) are setto Vread=6V, and GSL[1] and SSL[1] are set to 4-6V. Part of N SBLcapacitor voltages will start to discharge from initial 1.8V to Vss ifthe corresponding NAND cells are at erased E-state with Vte≦−0.7V withina predetermined discharge time. The remaining part of N SBL capacitorvoltages will not discharge and retain the initial 1.8V if thecorresponding NAND cells Vts>0, corresponding to an A-state.

Thus from the above explanation, after All-GBL Read operation of thisHiNAND array, the BBL lines in the selected Segment and the SBL lines inthe selected Group will trap respective Vss and 1.8V voltages inaccordance with the stored NAND Data pattern on the selected WL of theselected Block in the selected Segment in the selected Group of thisHiNAND array. After All-GBL Read, the local SBL_1[N] voltage is at 1.8Vor Vss but all N GBL lines is at 0V. All N GBL lines are still isolatedfrom all N SBL lines.

In a third step of the all-GBL HiNAND Read operation, charge-sharing isperformed for Read and Program-Verify operations. The charges in N SBLswould be dumped to N GBLs. In other words, the charge-sharing willhappen between N SBL lines and N GBL lines by turning on N 7V NMOSdevices MGBLp when DST[1] is set to 1.8V+Vt. After this third step, thevoltages of N GBL[N] are at ˜0.18V or 0V due to charge-sharing andC_(SBL)˜ 1/10C_(GBL).

Accordingly, a ΔV_(GBL) is only 0.18V−0V=0.18V, after the completion ofthe 3-step process of All-GBL Read or Program-Verify operation. Inanother embodiment, one additional step of All-BL Read andProgram-Verify operations is needed to amplify the small ΔV_(GBL)=0.18Vto a larger value so that it is a more reliable signal to be developedby a Latch SA of the present invention. In the HiNAND array architectureof the present invention, we propose to add a Multiplier that has anamplification factor being an integer no smaller than 2. In practice,the determination of the amplification factor is associated with theratio between the capacitances of GBL, SBL, and BBL lines. The detailsof ΔV_(GBL) voltage amplification and development will be explained insections below.

In addition, each GBL, SBL, or BBL line is associated with one NMOSdevice connected to a corresponding power line such as GBLps, SBLps, andBBLps, laid out in the X-direction (see FIG. 3D). These 1-poly NMOSdevices include MGBLs, MSBLs, and MBBLs and one device per each line ofGBL, SBL, and BBL. But a 2-poly NMOS device with a set programmed Vt canalso be used. There are other groups of N preferred NMOS devices inGroup 1 to connect between corresponding GBL[N], SBL_1[N], andBBL_1_1[N] lines in different BL-hierarchical levels. In order to savethe cost, the preferred number of metal lines is limited to 3 or less.For example, these devices include 1) N 1-poly NMOS transistors MGBLpbetween the top metal3 lines GBL[1] through GBL[N] (for all Groups) inthe Y-direction and one common power line of GBLps in X-direction; 2) N1-poly NMOS transistors MSBLp connected between top metal3 lines GBL[1]through GBL[N] and middle metal2 lines SBL_1[1] through SBL_1[N] (alsoin the Y-direction, for all Segments in Group 1), and 3) the N 1-polyNMOS transistors MBBLs connected between middle metal2 lines SBL_1[1]through SBL_1[N] and bottom metal1 lines BBL_1_1[1] through BBL_1_1[N](also in the Y-direction).

But the concept of a general m-level BL-hierarchical scheme for thispreferred HiNAND array should not be limited to only 3-levelBL-hierarchy. Note, the way of counting 3 BL-levels does not include themetal0 line that is reserved for all power lines such as GBLps, SBLps,and BBLps as well as one common NAND-String source lines of CSL[N], allbeing laid out in the X-direction.

In order to dramatically save the power-supply current to GBLps, SBLps,BBLps and CSL, it is preferable not to connect the plurality of lines ofGBLps, SBLps, BBLps, and CSL together because n-fold capacitance willoccur on above metal0 lines. Each line of GBLps, SBLps, BBLps, and CSLis preferably connected to a unique driver. Thus only the selected linesof GBLps, SBLps, BBLps, and CSL are supplied with Vdd or V_(Inhibit)voltages. The unselected lines and associated capacitances would not becharged, thus the fast speed and low-power consumption of multi-WLProgram and Read operations can be achieved in accordance with theHiNAND array of the present invention.

In a specific embodiment, the small ΔV_(GBL)=0.18V is amplified to amuch larger reliable ΔV signal by a DRAM-like SA as explained belowusing a preferred Multiplier. Practically, for a reliable and optimalΔV_(GBL) sensing, the mis-matched ΔVt and parasitic capacitance of twoinput-nodes Q and QB and MOS devices of the DRAM-like SA have to be welldesigned in the NAND circuit. Referring back to FIG. 1, in theconventional Odd/Even Read NAND scheme, all N GBLs are divided into twogroups of N/2 Odd numbered BLos and N/2 Even numbered BLes. Each pair ofBLo and BLe lines are directly connected to one corresponding Latch-type(INV1+INV2) SA through a GBL multiplexer made of a first pair of 20V1-poly NMOS devices MN1 and MN2 and a second pair of another 20V 1-polyNMOS devices MN3 and MN4.

By contrast, in the All-BL HiNAND memory circuitry of the presentinvention, a preferred Multiplier circuit shown in FIG. 4 is insertedbetween each GBL line, e.g., GBL[N], and a Latch SA. The DRAM-like SAcomprises several LV MOS transistors of MP3, MP2, MP4, MN2, MN4, MN3,MN7, and MN5 with several preferred control signals of RES, T3, T4, andT5. The conventional BL division of Odd-number BLo and Even-number BLewith one corresponding Multiplier is no longer required for this HiNANDdesign. As shown in FIG. 4, the detailed operations of the Multiplierplus a Connector and the Latch SA are explained below.

A) Multiplier operation: The Multiplier circuit is used to multiply thesmall detected ΔV_(GBL) by a multiplication factor that is developed atnode GBL and passed to BLP node with an approximate value of 0.18V asexplained in previous pages of this application. The ΔV_(GBL) ismultiplied by the multiplication factor preferred to be equal to orgreater than 2. As an example, the node GBL mentioned here is same asone GBL line (GBL[1] through GBL[N]) seen in FIG. 3D.

The input or detecting node of the Multiplier is BLP sensing node. Onemajor advantage of this HiNAND design over prior-art NAND is that theBLP sensing node is connected to its corresponding GBL metal3 linethrough the 20V NMOS transistor MN6 as it is biased into a conductionstate by coupling BIAS signal to Vdd. The BIAS voltage in theconventional NAND circuit is a MHV that is higher than Vdd such as 2.3Vin order to achieve a faster precharge of GBL to 0.9V because transistorMN6's Vt is about 1.2V typically for this 20V NMOS device havingthicker-gate oxide and longer channel length.

Conversely in the present HiNAND design, the voltage at GBL line,V_(GBL), is no longer 0.9V or Vss. Instead, it is a much reduced valueof 0.18V and Vss after charge-sharing between each 1.8V-SBL line and acorresponding 0V-GBL line. Therefore, to have a full ΔV_(GBL) (1.8V and0V) from GBL node to BLP sensing node, the BIAS voltage of 1.8V is largeenough without need to boost to HV of 2.3V. In the conventional NAND,the BIAS signal is not a constant MHV but varying from Vdd to 2.3V andback to Vdd during Program-Verify operation. Thus the control circuit ofBIAS is a little more complicated. In the present HiNAND circuit, withΔV_(GBL) and V_(GBL) being ˜0.18V and Vss, a Vdd constant voltage andVss is used for the BIAS signal to turn on or turn off the transistorMN6. Thus the BIAS control circuit becomes greatly simplified in theHiNAND design.

The output port of the Multiplier is OUTP node which outputs anamplified voltage signal after N-cycle multiplication operation of theMultiplier's input voltage at BLP sensing node, where N is themultiplication factor chosen from any integer number larger than 1depending on the required minimum ΔV_(GBL) value and speed and areatradeoff for the reliable sensing of the Latch SA that is connected tothe OUTP node.

In the Multiplier, selecting a larger M for a larger amplified ΔV_(GBL)will result in a larger silicon area and more sensing cycles of sampleand hold operation in each Multiplier circuit because more capacitorssuch as C[0] through C[M-1] are required (see FIG. 4). Practically, toomany cycles (M>3) of sample and hold operation on Multiplier's Mcapacitors to accomplish the final desired ΔV_(GBL) is not preferablefor this fast multiple-WL Program and Read operations. A preferredmultiplication factor M+1 is 2 or 3.

As shown in FIG. 4, every capacitor of C[0] through C[M-1] is connectedto two NMOS LV pass transistors. All capacitors C[0] through C[M-1] areconnected in series from the top OUTP node to a bottom node connected toIN[M]. The capacitance value of each capacitor C[0] through C[M1] can bemade the same or different. The type of capacitor is preferably made ofpoly1-poly2, metal3-metal2 or metal2-metal1 capacitors without a Vt dropfor a full coupling effect for this Multiplier's operation.

For example, the top poly2-plate of the first capacitor, C[1], isconnected to two LV NMOS transistors. One LV NMOS pass transistor isMN[1] with its left input node connected to a common input node BLP, itsgate tied to T[1] signal and its right output node connected to nodeIN[1]. The other LV NMOS transistor is MNN[1] with its drain nodeconnected to node IN[1] and its source node connected to Vss with itsgate tied to TP[1] signal. The bottom poly1 plate of the first capacitorC[1] is connected to top poly2 plate of the second capacitor C[2] (notshown in FIG. 4). The top common sensing node BLP is connected to apull-up 20V NMOS transistor of MN6 with its gate tied to BIAS signal andits drain node is connected to each corresponding GBL, for example,GBL[N] in the HiNAND array.

Similarly, the bottom poly2 plate of the last capacitor, C[M−1], isconnected to another two similar LV NMOS transistors. One passtransistor is MN[M] with its left input node connected to a common inputnode BLP, its gate tied to T[M] signal and its right output nodeconnected to node IN[M]. The other LV NMOS transistor MNN[M] with itsdrain node connected to node IN[M], its source node connected to Vsswith its gate tied to TP[M] signal.

The top plate of the capacitor, C[0], is connected to another LV NMOSpass transistor is MN[0] with its left input node connected to a commoninput node BLP, its gate tied to T[0] signal and its right output nodeconnected to OUTP node of the Multiplier. This OUTP node is alsopreferably coupled to a Connector circuit comprising two LV PMOS devicesMP1 and MP5 connected in series. The gate of MP5 is tied to OUTP node.The top drain node of MP1 connected to a VDDP signal and the bottomsource node of MP5 connected to a QB node, which is one input node ofthe Latch SA.

B) Connector circuit operation: There are many options for a preferredConnector circuit of the present invention. The major function of theConnector is to connect the multiplied voltage output from the OUTP nodeto one input of the Latch SA at QB node. As shown in FIG. 4, in aspecific embodiment, one of the preferred Connector circuit includes MP1and MP5 between Multiplier's output and Latch SA's input. Of course, forthose skilled in IC design, many other revisions of the Connectorcircuit can be designed but should be covered by this disclosure inprinciple.

In an embodiment, a first function of the Connector circuit (as seen inFIG. 4) is to reversely convert and amplify the input voltage ofΔV_(GBL) at OUTP node and couple to QB node, varying between a low valueof the reset voltage at 0V when MP5 is in a shut-off floating high Zstate when OUTP voltage is at 0.18V×N and a high value of the VDDPsignal when both MP1 and MP5 are biased into on-states when T3B signalis set to Vss and OUTP voltage is at Vss. The voltage-gain of theConnector equals to (VDDP−V_(QB))/ΔOUTP, where ΔOUTP=ΔV_(GBL) and theinitial reset voltage V_(QB) at QB node is 0V.

In another embodiment, a second function of the Connector circuit is toisolate the sensing QB node from the highly capacitive node at OUTP sothat one paired inputs of QB and Q nodes of the Latch SA can be easilydesigned to be fully symmetrical or tracking in terms of optimal layout,parasitic junction capacitance and reliable ΔV development between theQB and Q nodes of each Latch SA. The reset of QB node can beaccomplished by shutting off MP3 and turning on MN7 with biased one-shotconditions of setting RES and T4 signals to Vdd in the beginning of SAoperation. The T3B signal is to control on or off state of MP5. The VDDPvoltage is set to be OUTP voltage plus MP5's Vt level. If OUTP voltageis 0.36V with 2-fold amplification and MP5's Vt is 0.7V, then VDDPvoltage is about 1.06V (or less).

The Latch SA circuit is made of eight LV MOS transistors including threeLV PMOS devices MP3 and MP2 and MP4, and five LV NMOS devices MN3, MN7,MN2, MN4, and MN5. The source node of NMOS device MN5 is connected to aV_(REF) signal and its gate is tied to T3 signal and its drain node isconnected to Q node (another input) of the Latch SA. The drain node ofthe left MN7 NMOS device is connected to the QB node and its gate isconnected to a RES signal and its source node is connected to Vss. Thetop PMOS MP3's gate is connected to T4 signal and the gate of bottomNMOS MN3 is connected to T5 signal. The output nodes of the Latch SA areeither Q or QB with a preferred tracking and equal junction capacitancefor a reliable amplification of small ΔV of sensing signal present at Qand QB nodes initially.

For executing Multiple-WL and All-BL Read and Program-Verify operations,an on-chip PB is required like the conventional NAND circuit. Basically,the Multiple-WL and All-BL Read and Program-Verify operations of thepresent invention are more powerful and more flexible to allow both Readand Program-Verify performed simultaneously on more than one selectedWLs from more than one selected Segments from more than one Groups ofthe HiNAND array. But only one N-bit PB connected to N GBLs is needed.The single PB with N GBLs is designed to be shared by all selected WLsin the HiNAND array. Thus, the multiple page data read out frommultiple-selected WLs in multiple different Segments and Groups cannotbe presented into this shared PB with N GBLs simultaneously because thepage data contention would happen on N GBLs. This page data contentionwill result in fault reading and is not acceptable in NAND Readoperation. But in the preferred multiple-WL and All-BL Read andProgram-Verify operations of this present invention, this problem isproperly solved as explained below.

Since Read and Program-Verify operations are merely different in Readvoltage in the selected WL of the selected Block, the steps of operatingRead and Program-Verify are basic the same. Thus, the followingillustration is only focused on All-BL Read operation, though it shouldbe the same for Program-Verify operation for those skilled in the art.In today's NAND design specification, it shows it takes about 20 μS fora SLC Read, 60 μS for a MLC Read, and about 150 μS for a TLC Read. Themain improvement of the present All-BL Read operation within the HiNANDarchitecture over an Odd/Even Read operation in the conventional NANDare associated with efforts for a) Long GBLs precharged time reduction,b) WL set up time reduction, and c) BBL/SBL discharge time reduction.

In the conventional NAND single-WL Odd/Even Read operation, each GBL isprecharged to 0.9V first, regardless of BLe and BLo. The whole GBLs inwhole NAND array are precharged. This takes a long RC time with highpower consumption. The RC time, R_(precharge)C_(GBL), is fullydetermined by each GBL capacitance C_(GBL) and effective resistanceR_(precharge) of each 20V NMOS device of MN3 connected to BLe or MN4connected to BLo (see FIG. 1). Each GBL line capacitance value is about3-5 pf but R_(precharge) is determined by the bias and layout deviceconditions of MN3 and MN4. Typically, both MN3 and MN4 are made of along-channel and thicker oxide NMOS device to sustain a 19.5Vpunch-through across its Vds during a normal NAND Erase operation. This19.5V punch-through voltage is generated when TPW of NAND array iscoupled to a 20V high voltage for a bulk FN-tunneling effect in Eraseoperation. This 20V high voltage will be forwarded to GBL with 0.5V PNjunction drop through the NAND cell P/N junction source and drain nodesand reach to the drain nodes of MN3 and MN4. MN3 and MN4 have to blockthis 20V high voltage to the LV PB shown in FIG. 1. During GBLprecharge, the precharge current has to flow through MN3 to BLe and MN4to BLo. Thus the R_(precharge) of MN3 and MN4 are pretty high near 1MΩin final precharge step due to MN3 and MN4 gate voltages in Readoperation cannot be set too high otherwise the GBL precharge voltagecannot be limited below 0.9V. The Vt values of MN3 and MN4 are about1.4V and the gate voltages are set to be about 2.3V. Thus, the GBLprecharge time takes about ⅓ of Read latency, resulting int_(precharge)(NAND)˜7 μS. Its delay cannot be saved in NAND single-WLRead operation. But in the present HiNAND Read operation, assuming that16 SBL lines from 16 Groups are precharged at the same time, then thedelay is drastically reduced, resulting in t_(precharge)(HiNAND)˜7μS/16=0.4375 μS.

There is another long delay in conventional NAND single-WL Readoperation to charge all WLs with a long RC time, which isR_(charge)C_(WL). The R_(charge) is the resistance of one driver of 20VNMOS Segment transistor and C_(WL) is the WL capacitance. Particularly,the Vread voltage of non-selected multiple WLs in one selected Block is˜6V from a HV pump circuit. Due to the nature of the narrow-width andlong WL length without a metal-strapping on top of each WL, this Vreaddelay easily takes about 4 μS, resulting in t_(WLdelay)(NAND)=4 μS.Similarly, in this HiNAND read operation, if 16 selected WLs are beingprecharged at the same time, then the WL-charge-up delay can bedrastically reduced as calculated below, resulting int_(WLdelay)(HiNAND)=4 μS/16=0.25 μS.

Additionally, another long delay of the conventional NAND single-WL Readoperation results from a long RC time R_(discharge)C_(GBL) to dischargeall GBLs' precharged voltage of 0.9V. Unlike R_(precharge) is a deviceresistance of MN3 or MN4 device in t_(precharge) calculation, the valueof R_(discharge)=R_(select)+63×R_(read), assuming a selected 64T NANDString having one selected WL and 63 non-selected WLs. Each R_(read) ofmultiple non-selected cells in the selected String is small because highVgs−Vt value of the non-selected Cells with gate voltages at Vread=6.0V.Vgs−Vt (C-state)=Vread−Vt (C-state)=6.0V-4.5V=1.5V for the non-selectedNAND cells in the selected multiple WLs. But the selected Cell's gatevoltage is Vr. Vgs−Vt (Program-state)<0.4V, thus the resistance ofR_(select) is much larger, e.g., R_(select)>R_(read). The typicaleffective R_(discharge) is ranged about 1MΩ to 10MΩ for a String onlyconducting current ranging from 1 μA to 100 nA. As a result, theR_(discharge)C_(GBL)(NAND) is too long with t_(discharge)(NAND)=10 μS.If the HiNAND array effectively discharges 16 BBLs and 16 SBLs on thesame time, then t_(discharge)(HNAND)=10 μS/16=0.6250 μS.

In conclusion, the definition of simultaneous Read of this preferredmultiple-WL Read scheme means the simultaneous operations ofGBL-precharge, GBL-discharge, and WL charge-up delay. These operationsare followed by the non-data contention dump of page data from theselected page to one shared N-bit PB and N GBL lines. Multiple-WL pagedata is transferred to one PB one by one not at the same time. But thetransferring time of page data to the PB is as short as 1 μS or less,thus the total effective SLC Read delay can be potentially reduced fromconventional 20 μS to about 2 μS including the time of dumping page datato the PB. This is about 10-fold reduction in Read latency and mostsuitable for operating a very fast NAND memory system.

The operation procedure on how to reduce the delay times of GBLprecharge, GBL discharge, and WL charge-up by simultaneous operations ofmultiple-WL and All-BL Read related delays is shown below. Starting fromone selected WL from one selected Segment in one selected Group forAll-BL Read operation, the multiple-WL and All-BL Read will be extendedbased on the single-WL and All-BL Read. Therefore, the whole bit dataquality of the whole NAND chip can be easily built, recorded and handledby a controller chip for a superior NAND memory system.

Now, the operation of the preferred Multiplier (FIG. 4) will beexplained along with the GBL, SBL, and BBL structure in a HiNAND arraythat comprises J Groups per GBL, each Group comprising L Segments andeach Segment comprising K Blocks. The GBL is equivalent to GBL[N] (seeFIG. 3D) in accordance with a preferred set of bias conditions shown inFIG. 5.

As shown, the multiple-WL All-BL Read operation includes setting majorcontrol signals for executing following steps/functions that includePre-discharging GBL, Precharging SBL, Discharging SBL, Charge-sharing,Multiplying and Sensing, and GBL resetting. The Charge-sharing functionpreferably happens between each GBL metal3 line and each correspondingdivided SBL metal2 line and each divided BBL metal1 line to yield asmall V_(GBL) signal. The Multiplying function means to use a Multiplierto amplify the small detected signal ΔV_(GBL) to a larger ΔV at OUTPnode (of the Multiplier) which is reversely amplified further by aConnector circuit as a small yet sufficiently large ΔV signal which isfurther outputted to an input node QB of a Latch SA. The Sensingfunction (of the Latch SA) means a signal development of the small yetsufficiently large ΔV signal presented at two input nodes Q and QB ofthe Latch SA to a full amplified voltage of Vdd. Multiple controlsignals in association of the HiNAND3's multiple-WL and All-BL Readoperation are listed below:

-   -   a) G_PRE: This is gate signal of 1-poly NMOS Group-select        transistor MGBLs used to connect all N GBL metal3 lines in        Y-direction to one metal0 bus GBLps in X-direction        (perpendicular to the Y-direction) simultaneously. All N GBLs        include GBL[1] through GBL[N].    -   b) GBLps: This is a metal0 power line supplied for N GBL metal3        lines. If GBLps is coupled to 0V, then it is used to discharge        all N GBLs to 0V for resetting. If GBLps is applied with Vdd,        then it is used as a power line to precharge all N GBLs to Vdd        (or other desired GBL voltages). There is only one GBLps power        line in parallel to all WLs in the X-direction per one Group of        the HiNAND array.    -   c) DST: This gate signal is used to control N 1-poly NMOS        Segment-select transistors MSBLp for connecting top N GBL metal3        lines with the middle N SBL metal2 lines.    -   d) B_PRE: This gate signal is used to control N 1-poly NMOS        Block-select transistors MBBLs for connecting the middle N SBL        metal2 lines with the bottom N BBL metal1 lines.    -   e) BBLps: This is the metal0 power lines supplied for N BBL        metal1 lines. One BBLps line in parallel to the WLs in the        X-direction can be shared by two neighboring Segments in one        HiNAND Group.    -   f) CSL: This is a common horizontal (X-direction) metal0 source        line of HiNAND-String (similar as the prior-art NAND). In an        embodiment, one CSL metal0 line is shared by two adjacent HiNAND        Blocks source nodes mirrored in the Y-direction. In another        embodiment, CSL line associated with every Block in all Segments        within a same Group can be connected together. If Vdd is        required during single or multiple-WL Program, CSL lines are        preferably not connected together to reduce the        power-consumption. In other words, one option is to have a        separate CSL line per one paired mirrored HiNAND Strings.    -   g) SEC: It is a common gate signal of N 1-poly Segment-select        NMOS transistors MSBLp respectively connecting between each SBL        metal2 line and each BBL metal1 line.    -   h) SSL: This is the gate signal of NAND String-select NMOS        transistor MS. During Read, the selected SSL is set to ≦Vdd to        reduce channel voltage in the String of NAND cells, while the        unselected SSLs=Vss.    -   i) S_PRE: This is the common gate control of the NMOS 1-poly        Segment-select transistor, MSBLs, for precharging or discharging        the voltages on N SBL_1[N] metal2 lines of all Segments in each        NAND Group during Read operation. For HiNAND Read operation,        only one S_PRE line in X-direction is required per one NAND        Group.    -   j) SBLps: This is a metal0 power line per NAND Group. If        SBLps=0V, then it is used to discharge all N SBL lines to Vss.        If SBLps is applied to a precharge voltage Vpch, then it is used        to precharge all N SBL lines to Vpch for All-BL Read and        Program-Verify. The Vpch ranging from Vdd to V_(Inhibit)=7V can        be charged for All-BL Read and Program-Verify operations.    -   k) GSL: The is the common gate signal of NAND String-select        transistor MG. This one horizontal line laid out in the        X-direction per NAND String. During Read, the selected GSL is        coupled to a high pass voltage Vpass2 about 8-10V to pass Vdd up        to 7V to the selected cell's drain node, while unselected GSLs        are at Vss=0V.    -   l) WL: This is applied to Vrm for selected WL while the        un-selected WLs=Vread=6V, where m=1 only for a SLC Read, m=1, 2,        3 for a MLC Read, m=1, through 7 for a TLC Read, and m=1,        through 15 values of Vrm for a XLC Read. All above Read        operation is within a preferred All-BL Read scheme of HiNAND        array.    -   m) BBL: This is the bottom-level metal1 BLs. It is also the        shortest BLs with least capacitances. This BBL capacitance is        used for storing and latching the V_(Inhibit) voltage initially        for N BBL_1_1[N] lines for direct Program operation without a        commonly used self-boosting scheme in the conventional NAND.    -   n) SBL: This is the middle-level metal2 BLs and it is mainly        used to store the Vdd precharge voltage for All-BL Read        operation on all N SBL_1[N] lines.

o) GBL: This is the top-level global BL metal3 lines.

In a specific implementation, the sequences of the preferred All-BL Readoperation will be illustrated with reference to FIG. 5 and the HiNANDcircuit shown in FIG. 3D. The preferred whole All-BL and Multiple-WLRead operation of the HiNAND array is preferably divided into severalsteps as shown below.

-   -   1) Pre-discharge period for all N GBL/SBL/BBL lines:        -   Initially, before any Read, all N GBLs, N SBLs, N BBLs are            preferably to be pre-discharged to 0V by the following bias            conditions in the selected Groups.        -   Note, for this HiNAND Multiple-WL and All-BL Read, multiple            Group selections are allowed.        -   a) Setting GBLps, SBLps, and BBLps to Vss.        -   b) Setting G_PRE, B_PRE_1, and S_PRE[1] to Vdd.        -   c) MGBLp, MSBLp and MBBLp are all in conduction state.        -   d) The PB has to be isolated from GBL[N] to avoid GBL            leakage.    -   2) Precharge period:        -   This operation is only done on the selected N SBL lines and            N BBL lines, rather on N GBL lines. In this HiNAND array,            Read and Program-Verify operations would not require any            precharge on the long and heavy GBL capacitance. Instead,            the precharge is preferably done on the shorter SBL lines            and BBL lines. As explained previously for dividing the            HiNAND array into J (e.g, J=10) Groups, the            C_(SBL)˜1/J×C_(GBL). During the precharge period, all N GBL            lines are isolated from all N SBL lines. But the N SBL            lines' voltages would be equal to all N BBL lines. In other            words, in All-BL single-WL Read operation, the middle-level            SBL metal2 lines and the bottom-level corresponding BBL            metal1 lines are precharged to Vpch voltage ranging from            Vdd=1.8V to V_(Inhibit)˜7V. The Vpch precharged voltage can            come from either one of two power lines of SBLps and BBLps            or both. Both transistors MSBLp and MBBLp are all in fully            conduction state with respective gates S_PRE[1] and SEC_1[1]            (for selected Group 1) being set to Vpass2 (˜Vpch+Vt˜10V)            voltage while DST[1] signal is set to Vss=0V to shut off the            precharge current from leaking to GBL through N MGBLp            transistors. After this period, the following conditions are            set.        -   a) N GBLcap at 0V.        -   b) SBLcap are charged simultaneously to Vpch voltage from            Vdd to V_(Inhibit)=7V for independently selected SBLs in the            selected one or more Groups.        -   c) SBLcap at Vss=0V for unselected SBLs in the selected one            or more Groups.        -   d) BBLcap are charged simultaneously to Vpch voltage from            Vdd=1.8V to V_(Inhibit)=7V for selected BBLs in the            independently selected Segments of the selected one or more            Groups.        -   e) BBLcap at Vss=0V for unselected BBLs in the selected            Segments of the selected one or more Groups.        -   g) SSL is set to a bias voltage no greater than Vdd to the            gate of String-select transistor MS to limit the channel            voltage of cells after precharge. GSL is set to 0V to close            the path to the CSL at ground.    -   3) Selected BBL lines discharge period in accordance with the        multiple pages' data stored in the multiple selected pages: Only        one page of physical WL per Segment is selected and there can be        multiple selected pages in different selected Segments. This        operation is only done on the selected N SBLcap and N BBLcap,        rather on N GBLcap lines. After the discharge period, the        followings conditions are set.        -   a) N GBLcap at 0V, not affected by this period.        -   b) Part of N BBLcap are retained at Vpch (Vdd=1.8V to            V_(Inhibit)=7V) for those selected Off-cells with Vt>Vrm, in            the multiple selected WLs in the selected Segments of the            selected Groups (m=1 for SLC, m=1, 2, 3 for MLC, . . . ).        -   c) Remaining part of N BBLcap are discharged through            String-select transistor turned on by setting GSL to            Vpass2˜10V to Vss=0V for selected On-cells with Vt<Vrm, in            the different selected Segments of the selected Groups.        -   d) Part of N SBLcap are retained at Vpch (Vdd=1.8V to            V_(Inhibit)=7V) for selected Off-cells with Vt>Vrm, in the            selected Segment of the selected Groups because no discharge            happens to the corresponding part of N BBLcap by setting SEC            signal to Vpass2˜10V to turn on each bridge transistor MSBLp            between each SBL and corresponding BBL.        -   e) Remaining part of N SBLcap are discharged to Vss=0V for            selected On-cells with Vt<Vrm, in the selected Segment of            the selected Groups.        -   f) N BBLcap and N SBLcap are at 0V for each unselected            Segment within unselected Groups.    -   4) Charge-Sharing period (CS):        -   This operation is only done between N SBLcap and N BBLcap            and N GBLcap. After the discharge period, the followings            conditions are set by fully turning on MGBLp with the            selected DST signal. Since GBLcap is 10×SBLcap (assuming            J=10 Groups), thus the Vpch of 1.8V or 7V initial precharged            values in SBLs is approximately reduced to Vpch/J of about            0.18V or 0.7V as explained above. Thereby the detailed            charge-sharing operation is skipped here for simplicity.        -   Before executing CS between GBL and SBL+BBL, there is a            concern of coupling effects between two adjacent SBLs and            BBLs (Left and Right) which may lower the final voltages of            both BBL and SBL, thus affecting the final diluted GBL            voltage below 0.18V if the precharged voltage is 1.8V. If            that is the case, one solution is to increase the initial            precharged voltage Vpch from 1.8V to a higher voltage to            compensate for the coupling noise effect. In case when the            BL-BL coupling effect is getting worse as NAND technology            migrates to more advanced nodes, the precharge voltage Vpch            is preferably increased to 7V to provide more margins to            mitigate the coupling effect.        -   a) Voltages of part of N GBLcap, N SBLcap, or N BBLcap            remain as the initial value of 0V if the selected cells with            Vt<Vrm, in the different selected Segments of the selected            Groups.        -   b) Voltages of remaining part of N GBLcap, N SBLcap, or N            BBLcap drop to Vpch/J (e.g, 0.18V or 0.7V) if the selected            cells with Vt>Vrm, in the different selected Segments of the            selected Groups.        -   c) N BBLcap and N SBLcap are at 0V for each unselected            Segment within unselected Groups.        -   Note, all the final N GBL voltages in accordance with the            stored page data would be coupled to each corresponding node            of BLP through MN6 shown in FIG. 4. Unlike the prior-art            NAND to pass Vdd-Vt, the present invention is to pass 0.18V            only. As a result, the BIAS signal at Vdd is enough. Thus            BIAS control circuit does not need a HV so that the BIAS            circuit becomes simpler.    -   5) Multiplying period.        -   Using a precharge voltage of Vpch=Vdd=1.8V as an example,            the final GBL voltage V_(GBL)=0.18V or 0V is still too small            for the normal operation of Latch SA shown in FIG. 4 if the            device mismatch factors of SA are taken into consideration            as explained in previous sections of the present            application. Thus, a Multiplier circuit is needed to amply            the V_(GBL) to a voltage by several folds. The detailed            operations were explained in prior pages and are skipped            here for simplicity.        -   After this period, the output voltage of the Multiplier is            V_(OUTP)=3×V_(GBL) if a three-cycle Sample and Hold            Multiplier is used. The REF voltage is preferably set to be            half of 3×V_(GBL) generated by a HV pump circuit with a            resistor-divider, not shown. The whole HiNAND can have only            one VREF circuit. Then the ΔV between QB and Q node of            SA=½×3×V_(GBL)=1.5×V_(GBL)=1.5×1.8V=2.7V which is large            enough to compensate the Vt or other device mismatch between            MP4+MN4 and MP2+MN2.    -   6) Sensing period: This operation is something like the ΔV        signal development by a Latch, which is comprised of 3 LV PMOS        devices of MP3, MP2 and MP4 and 3 LV NMOS devices of MN2, MN4        and MN3 plus 2 NMOS reset transistors of MN7 and MN5. There are        5 steps of SA operations.        -   a) Connector disconnect step:            -   By setting T3B=Vdd and VDDP=V_(OUTP)+Vtp, thus MP1 would                be in non-conduction high Z state, The Vtp is the Vt of                PMOS transistor MP5. The VDDP voltage can be generated                from a common voltage-mirror circuit like MP1+MP5. For                those skilled in circuit design, many circuit options                can be sued to generate VDDP+Vtp. Thereby, the details                are not described here without affecting the explanation                of the operating principle of the Connect circuit with                two PMOS devices MP1 and MP5 (see FIG. 4).        -   b) QB and Q reset step:            -   Once Connector in high Z state, the QB and Q can be rest                without leaking any DC current from VDDP to Vss. Both QB                and Q nodes are predischarged first through MN7 and MN5                by setting RES and T3 signals to Vdd in an one-shot                pulse with T4 signal being set at Vdd and T5 signal                being set at Vss.        -   c) A period of latching two input voltages to QB and Q from            V_(OUTP) and V_(REF) for Latch SA. This is done by setting            T3B signal to Vss and T3 signal to Vdd and VREF=0.5VDDP by            the one-shot pulse.        -   d) T5 pull-down development period:            -   This operation is done by ramping up T5 signal from Vss                to Vdd.        -   e) T4 pull-up development period:            -   This operation is done by ramping down T4 signal from                Vdd to Vss.        -   After above 5 steps, a fully development Vdd vs Vss voltage            will be generated at QB and Q nodes of each Latch SA with            the following results:        -   f) If V_(OUTP)=3×V_(GBL)=0.54V, then QB=Vss and Q=Vdd        -   g) If V_(OUTP)=0V, then QB=VDDP and QB=Vdd and Q=Vss        -   One of above two data at QB and Q nodes can be sent out to            the corresponding bits in PB to report the detected storage            data for SLC, MLC, TLC and XLC storages.        -   After the sensing period (which is executed very fast            following the multiplying period), the N GBLs are reset by            switching G_PRE to Vdd to turn on the GBL-select transistors            MGBLs for cleaning up all GBLs by dumping the charges to            ground (with GBLps line at the ground level 0V) to make next            page's Read operation ready.

FIG. 6 shows the preferred table of Multiple-WL & All-BL Programoperation in HiNAND array according to an embodiment of the presentinvention. It starts out from setting one latch of one selected Segmentof at a time. The number of selected latches, M, can be flexiblyselectively set to be more than one Segment in different Groups in theHiNAND array for M-fold reduction in Program time because M WLs would beselected for simultaneous Program.

Firstly, a check of the total selected latches being set correctly asdesired for performing simultaneous Multiple-WL Program in all selectedSegments and in the selected Groups. If all desired latches of theselected Groups are not set yet, then multiple Segments' latch settingwould be continued. Once the setting procedure of all latches of allselected Segments are being successfully set, then the Multiple-WL &All-BL Program operation would be proceeded.

The major control signals are listed and explained below.

-   -   a) G_PRE: This is gate signal of 1-poly NMOS Group-select        transistor MGBLs used to connect all N GBL metal3 lines in        Y-direction to one metal0 bus GBLps in X-direction        (perpendicular to the Y-direction) simultaneously. All N GBLs        include GBL[1] through GBL[N]. The G_PRE signal can be set to        Vdd+Vt for fully passing Vdd from the power line of GBLps to all        N GBLs or set to Vdd for discharging or resetting the N GBLs to        0V if the metal0 bus GBLps is grounded.    -   b) GBLps: This is the metal0 power lines for N GBL metal3 lines.        If GBLps is at 0V, then it is used to discharge all N GBL lines        to Vss. If GBLps is coupled to Vpch voltage ranging from Vdd to        7V, then it is used to precharge all N GBL lines to Vpch voltage        or other desired GBL voltages. There is only one horizontal        GBLps power line in parallel to WLs per one Group of the HiNAND        array.    -   c) DST: This gate signal is used to control N 1-poly NMOS        Segment-select transistors MSBLp for connecting top N GBL metal3        lines with the middle N SBL metal2 lines.    -   d) B_PRE: This gate signal is used to control N 1-poly NMOS        Block-select transistors MBBLs for connecting the middle N SBL        metal2 lines with the bottom N BBL metal1 lines. In an        embodiment, B_PRE is preferred to be at V_(Inhibit)+Vt        (Vpass2˜10V) to precharge the N BBLs up to V_(Inhibit) voltage        ˜7V from the corresponding BBLps line.    -   e) BBLps: This is the metal0 power lines for N BBL metal2 lines.        If BBLps is at 0V, then it is used to discharge all N BBL lines        to Vss. If BBLps is coupled to Vpch, then it is used to        precharge all N BBL lines to Vpch voltage for All-BL Read and        Program-Verify operations. For example, if BBLps is set to        V_(Inhibit), then it is used to precharge all N BBL lines to a        value of above 7V for All-BL Program operation. In an        embodiment, there is only one BBLps line in parallel to WLs per        one Segment of one Group in the HiNAND array. In an alternative        embodiment, each BBLps line can be shared by two neighboring        mirror Segments in one Group in the HiNAND array.    -   f) CSL: This is a common horizontal metal0 source line of a        HiNAND String. One CSL metal0 line is shared by two adjacent        HiNAND Strings mirrored in Y-direction. If CSL is used for        grounding, every CSL lines for each Block in all Segments within        one Group can be connected together. If Vdd is required during        Single or multiple-WL Program, CSL lines are preferably not        connected together to reduce the power-consumption. In other        words, one option is to have a separate CSL line per paired        mirrored HiNAND Strings.

g) SEC: It is a common gate signal of N MSBLp which is a divided 1-polySegment NMOS transistor coupled between each SBL metal2 line and eachBBL metal1 line. During Program and Program-Inhibit operations, in anembodiment, the preferred voltage of SEC is set to V_(Inhibit)+Vt (e.g.,Vpass2) is required to allow the full passage of V_(Inhibit) voltageprecharged from the corresponding SBLps line through N SBL_1[N] lines toreach its corresponding N BBL_1_1[N] lines.

-   -   h) SSL: This is the gate signal of NAND String-select NMOS        transistor MS.    -   i) S_PRE: This is the common gate control of the String-select        NMOS 1-poly transistors, MSBLp, for precharging or discharging        the voltages on N SBL_1[N] metal2 lines of each NAND Group. For        the HiNAND Read operation, only one horizontal S_PRE line is        required per one NAND Group.    -   j) SBLps: This is a metal0 power line per NAND Group. If SBLps        is at 0V, then it is used to discharge all N SBL lines to Vss.        If SBLps is coupled to Vpch (e.g. Vdd), then it is used to        precharge all N SBL lines to Vdd for All-BL Read and        Program-Verify operations. If SBLps is set to V_(Inhibit), then        it is used to precharge all N SBL lines to a value of above 7V        for All-BL Program, Program-Verify, and Read operations.    -   k) GSL: This is the common gate signal of NAND String-select        transistor of MG. This is one horizontal (X-direction) line per        NAND String. During page Program, the selected        GSL=V_(Inhibit)+Vdd (or Vpass2) to pass full V_(Inhibit) to the        selected programmed cells' channels, while unselected GSLs=Vss.    -   l) WL (selected pages): Each WL means one physical NAND page.        During Program, the selected WL=Vpgm, while the un-selected (and        erased) WLs=Vpass1˜7V, unselected adjacent programmed        WLs=Vpass2˜10V, and other unselected programmed WLs=Vdd.    -   m) WL (unselected pages): During Program, the unselected        WLs=Vss.    -   n) BBL: This is the bottom-level metal1 BLs. It is also the        shortest BLs with least capacitance. This BBL capacitance is        used for storing and latching the V_(Inhibit) voltage initially        for N BBL_1_1[N] lines initially for direct Program operation        without a SB scheme as commonly used in the conventional NAND.    -   o) SBL: This is the middle-level metal2 BLs and it is mainly        used to store the precharge voltage for All-BL Read and        Program-Verify operations on all N SBL_1[N] lines.    -   p) GBL: This is the top-level metal3 BLs.

Now, the multiple and All-BL Program would be explained. The Multiple-WLand All-BL Program operation is divided into following steps inaccordance with FIG. 6 and HiNAND array circuit of FIG. 3D:

-   -   1) Predischarge GBL/SBL/BBL:        -   In order to predischarge all N GBLs, N SBLs, and N BBLs,            setting gate control signals G_PRE, B_PRE (selected), S_PRE            to Vdd to turn on transistors MGBLs, MBBLs, MSBLs along with            grounding GBLps, SBLps, BBLps lines to 0V. Thus all charges            in metal3 GBLcap, metal2 SBLcap and metal1 BBLcap are being            discharged to Vss through the corresponding power lines            simultaneously to save time.    -   2) Precharge BBL:        -   By using the preferred non-SBPI method of the present            invention, all BBL lines are precharged with a            MV=V_(Inhibit)˜7V. Note, when precharging BBLcap, all the            corresponding SBLcap and GBLcap are blocked from BBLcap (or            BBL lines) to reduce the total capacitance of each BBLcap.            As a result, the least precharge current can be achieved. In            order to make sure only the selected N BBL lines are set for            precharging MV, the corresponding N Segment-select            transistors MSBLp are being shut off by grounding SEC signal            so that the N BBL lines are isolated from corresponding N            SBL lines. Since N BBL lines are blocked from N SBL lines,            thus they are also blocked from N GBLs.        -   a) To precharge N BBL lines, setting B_PRE signal to            Vpass2˜10V to pass MV=V_(Inhibit)˜7V through MBBLs from            BBLps line.        -   b) Setting SSL signal to Vpass2˜10V is to precharge each            HiNAND String from bottom WLs (WL[64]) to the source node of            the corresponding selected cell MC through a Block-select            transistor MS. The top cells above the selected cell in the            String are all erased cells with a negative Vte≦−0.7V.        -   c) To reduce the Vds of the Block-select transistor MG of            each HiNAND String, a common source line CSL is coupled to            Vdd.        -   d) To prevent leakage from N BBLs to N SBLs, SEC signal is            set to 0V and DST signal is set to 0V to further isolate the            SBL with GBL.        -   e) After this step, all N BBLcap associated with the            selected Block in the selected Segments of the selected            Groups is charged to MV-7V supplied from the power line            BBLps, but N SBLcap and N GBLcap remain at 0V.        -   f) Besides to precharge N BBLs to MV voltage and all            selected WL voltages are also being set up to the desired            first Vpass1 to save time delay. Thus, V_(WL)=Vpass1˜10V,            regardless of selected and unselected WLs before program            starts.        -   Note, the BBL precharge is performed simultaneously in            multiple selected Blocks respectively associated with            different Segments in one or more Groups, which is a very            time efficient operation step with an estimated precharge            time in just 1-3 μs for the HiNAND array in the present            invention.        -   Also note, the BBL precharge can also be performed through            SBLps power line by opening each Segment-select transistor            MSBLs (setting S_PRE to Vpass2) and opening each            Segment-transistor MSBLp (setting SEC to Vpass2).    -   3) Latch MV in N BBLcap and turn-off MV Precharge period:        -   a) B_PRE (selected Block) is switched from the Vpass2 to Vdd            first to shut off the current flow from each BBL to the            power line BBLps which is retained at MV. Then B_PRE is            further reduced to 0V to turn off the Segment-select            transistor MBBLs, while turning off BBLps from MV to 0V, to            prevent any leakage from N BBL lines to BBLps power line.        -   b) SSL (selected Block) is lowered from Vpass2 to Vdd=1.8V            so that the trapped charges in the HiNAND String does not            leak out. Further, SSL is retained at the Vdd while the            MV=V_(Inhibit) voltage is supplied for the String from the            local BBLcap without using a HV pump circuit. In other            words, MV˜7V voltage is solidly coupled to those            program-inhibited NAND cells directly without using the            conventional unreliable SBPI methods such as SB, LSB, and            EASB.        -   c) After this step, all N BBLs of the selected Block in            selected Segments are charged (or trapped) to MV˜7V voltage            and all leakage paths have been shut off to prevent leakage            current.    -   4) Sample current data (Voltage conversion of PB's Vdd/Vss to        MV/Vss):        -   DST is switched to Vpass1>Vdd to first turn on each            Group-select transistor MGBLp to allow PB's data signal            (Vdd/Vss) to pass from N GBLs to N SBLs. Then, SEC signal is            set to Vdd (after the SBLs becomes Vdd/Vss level) to allow            full passage of MV=V_(Inhibit)˜7V voltage at each BBLcap to            drop to zero if the corresponding SBL is at Vss=0V level            from the PB while to retain the V_(Inhibit)˜7V in BBL if the            corresponding SBL is at Vdd level from the PB. Now, all N            BBLcaps in a selected Segment (precharged to MV up to            V_(Inhibit) voltage) are sampled to convert Vdd/Vss levels            in accordance with a page data stored in N-bit PB to            V_(Inhibit)/Vss levels.        -   a) If PB's data bits are 0V, then the capacitances BBLcap,            SBLcap, GBLcap of corresponding BBL, SBL, GBL lines            respectively drops to 0V.        -   b) If PB's bits are Vdd, then the corresponding capacitance            BBLcap retains V_(Inhibit) voltage but SBLcap and GBLcap are            at Vdd.        -   After this step, the channels of the selected HiNAND cells            in the selected page would be either 0V or V_(Inhibit)            voltage level converted from Page Buffer data of 0V or Vdd            level. It is ready for next page Program on the selected WL.    -   5) Hold current data:        -   a) One-page (one-WL) data Sample and Hold:            -   Once all one-page program data being latched with                V_(Inhibit) or Vss voltage in all Strings of the                selected Block, then all the NMOS devices MSBLp                associated with the whole page have to be shut off by                switching SEC signal to Vss to isolate each BBLcap from                each corresponding SBLcap to free the buses of SBLs and                GBLs for other concurrent operations.        -   b) Multiple-page (multiple-WL) Sample and Hold:            -   This multiple-page data Sample and Hold is done on                one-by-one basis because the PB is shared by all                selected pages. Any selected single page can be                independently and sequentially loaded with single page                data from the PB via the shared buses of GBL and SBL                lines. Once the Sample and Hold for the currently                selected page is done, both SBL and GBL buses will be                freed, then the PB will be loaded with next page data                for performing next Sample and Hold for the next one                page. Until all multiple pages of BBLcaps being loaded                with the desired multiple page data in multiple isolated                BBLcap arrays, then multiple-WL Program operation can be                performed simultaneously.    -   6) Multiple-WL Program simultaneously:        -   The Multiple-WL Program operation of the present invention            can be started concurrently after the successful            multiple-page Sample and Hold step and the multiple selected            WLs' program voltages being increased from initial Vpass2            ˜10V to a final Vpgm of ˜20V by using an ISSP scheme with            0.2V increment per step. In a specific embodiment of the            non-SBPI multiple-WL Program scheme, all selected WLs of            multiple selected Blocks are located at relative same String            location (e.g., WL[1]) in multiple selected Segments. Under            this scenario, one single Vpgm voltage can be generated            simply from one common row decoder. In an alternative            specific embodiment of the multiple-WL Program scheme,            Program operations on different WL locations in different            Strings and Blocks in one or more different Groups can also            be applied. Under this scenario, multiple different Vpgm            voltages have to be respectively latched first in parasitic            poly capacitors associated with the selected multiple WLs            before the Multiple-WL Program operation is started.

FIG. 7 shows a preset set of WLs Program voltages by using a preferrednon-Self-Boosting Program-Inhibit scheme for Multiple-WL and All-BL Readand Program-Verify operations in the HiNAND array according to anembodiment of the present invention. So far, in all prior-art NANDSelf-Boosting-Program-Inhibit (SBPI) methods is used with theV_(Inhibit)=Vdd rather than V_(Inhibit)≧7V being coupled to those GBLsof the program-inhibited cells and Vss for the selected programmedcells. There are three major SBPI methods such as SB, LSB and EASB. Allof them adopted the SB scheme. The performance becomes unreliable whenNAND node is scaled below 3×nm due to the BL-BL and WL-WL proximitycoupling effects. The final V_(Inhibit)≧7V in SBPI scheme is generatedfrom initial Vdd-Vt by WL and cell channel coupling effect. Theadvantage of the SBPI scheme is the use of low-power of Vdd, rather than7V is coupled to long and large GBL capacitance, thus the PB can bebuilt by LV devices. But, the SBPI scheme is performed in Odd/Even BL2-cycle page Program due to the concern of BL-BL coupling effect.Particularly, when one program-inhibited GBL is sandwiched by twoadjacent NAND cells biased at 0V, the boosting voltage will be degradeddue to more parasitic coupling capacitance from two adjacent GBLs.

Conversely, in the HiNAND of the present invention anon-Self-Boosting-Program-Inhibit method is proposed for performing aHiNAND program operation as shown in FIG. 7. The program-inhibit voltageV_(Inhibit)≧7V replaces Vdd used for the conventional NAND Programoperation. V_(Inhibit)≧7V is also coupled to those GBLs of theprogram-inhibited cells and Vss is applied for the selected programmedcells. But, these V_(Inhibit) voltages≧7V are not coupled from the longGBLs from the PB. Instead, they are coupled from local short BBL linesthat are supplied from the corresponding selected BBLps power lines.After one-shot of pulse of precharging the selected N BBLs lines withthe V_(Inhibit) voltages, the V_(Inhibit) voltage is then latched as atemporary V_(Inhibit) HV supply. The details have been explainedthroughout the specification.

Since the V_(Inhibit) and Vss voltages are also supplied from HiNANDString top through the multiple erased cells with Vte≦−0.7V. Thus theun-programmed top WLs (from WL[1] to WL[m−1], if WL[m] is the currentlyprogrammed WL) are preferably coupled to a Vpass2 voltage. The Vpass2 ispreferably set to be a about than half of Vpgm of about 20V, for exampleVpass2˜10V, to avoid the WL-WL punch-through between one selectedprogrammed WL, WL[m], and the adjacent one (programmed) WL[m+1]. Othernot-yet-programmed WLs, WL[m−1] up to the top WL[1] will be set just ata lower voltage Vpass1 which is selected to be slightly higher than amiddle level precharge voltage MV that is trapped in the local BBLcap.

The main concept of this preferred non-SBPI scheme is to set WL voltagesto ensure that the programmed WLs are coupled to the Vpass2 voltage onlyone time and Vpass1 WL stress only happens more than one time to thoseerased cells in the un-programmed unselected WLs, because the erased Estate Vte is less sensitive to Vpass1 stress than A, B and C programmedMLC state or other 7 programmed states of TLC storage. As a result, themethod shown in FIG. 7 has achieved almost negligible Vpass1 WL stressto those HiNAND cells storing the programmed Vts, regardless of SLC,MLC, TLC and even XLC storage types.

The Vpass1 voltage can be 2-3 Volts below Vpass2 of 10V. Because Vpass1is the gate voltage to fully pass 7V V_(Inhibit) voltage through thechannels of erased cells which has a negative Vte, Vpass1=7V is enough.But Vpass2 is the gate voltage designed to fully pass 7V V_(Inhibit)voltage to the program-inhibited cells in the selected WL[m] through theprogrammed cells. Thus Vpass2 voltage is preferably set to be 10V to getfull V_(Inhibit) passage without any drop for a reliable non-SBPI of thepresent invention.

Note, the top NAND String-select transistor has Vds=0V (both drain andsource nodes are at V_(Inhibit) Voltage) during this preferred non-SBPImethod, thus the Gate-induced drain leakage (GIDL) effect is completelyeliminated. Thus a dummy WL transistor between the top cell associatedwith WL[1] and the top String-select transistor is not needed.Similarly, the bottom String-select transistors Vds is smaller than 7V,thus GIDL effect is also dramatically reduced and bottom dummy is notneeded. Thus, this non-SBPI design is more reliable for SLC, MLC. TLCand XLC programming in 1-cycle All-BL Program operation.

Although the above has been illustrated according to specificembodiments, there can be other modifications, alternatives, andvariations. It is understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication and scope of the appended claims.

What is claimed is:
 1. A high-density NAND (HiNAND) circuit withmulti-level BL-hierarchical architecture for lowering disturbance,power-consumption, and latency in Program, Program-Verify, Erase-Verify,and Read operations, the HiNAND circuit comprising: a matrix of NANDmemory cells divided to J Groups in column-direction having N global bitlines (GBLs), each Group being divided to L Segments in thecolumn-direction, each Segment being further divided to K Blocks in thecolumn-direction, each Block comprising N Strings in thecolumn-direction or M Pages in row-direction, each String comprising MNAND memory cells connected in series sandwiched by a firstString-select transistor and a second String-select transistor, eachNAND memory cell in a Page being associated with a word line (WL), J, L,K, M, and N being integer numbers, wherein J is at least equal to orgreater than 8; a BL-hierarchical structure comprising N metal3 linescorresponding to N metal2 lines and further to N metal1 lines all beingparallel to each other along the column-direction, each metal3 linebeing used as one the N GBLs across all J Groups of NAND memory cells,each metal2 line being used as one of N sub-BL lines (SBLs) associatedwith each column of NAND memory cells across all L Segments in eachGroup, each metal1 line being used as one of N sub-sub-BL lines (BBLs)across all K Blocks in each Segment; a plurality of metal0 lines laidout along the row-direction, the plurality of metal0 lines including atleast one common source line connected respectively via the firstString-select transistor to each of the N Strings of NAND memory cellsin one or more Blocks of one or more Segments of each Group, a firstpower/Vss line for all J Groups, a second power/Vss line for all LSegments in a Group, and a third power/Vss line for all K Blocks in apair of Segments in one Group; N first GBL-select transistors commonlycontrolled by a first gate signal to respectively couple the N GBLs withthe first power/Vss line; N second GBL-select transistors commonlycontrolled by a second gate signal to respectively couple the N GBLswith the corresponding N SBLs; N first SBL-select transistors commonlycontrolled by a third gate signal to respectively couple the N SBLs withthe second power/Vss line; N second SBL-select transistors commonlycontrolled by a fourth gate signal to respectively couple the N SBLswith the corresponding N BBLs; N BBL-select transistors commonlycontrolled by a fifth gate signal to respectively couple the N BBLs withthe third power/Vss line; and a Page Buffer circuit respectively coupledto the N GBLs and configured to store and supply multiple logic pagedata in the form of sequential pipe-line; wherein the BL-hierarchicalstructure in accordance with a preferred set of bias voltage conditionsassociated with at least the first gate signal, the second gate signal,the third gate signal, the fourth gate signal, and the fifth gate signalis configured to allow temporary storages of program voltage andprogram-inhibit voltage in the multiple BBLs in one or more Segments ofone or more Groups for performing multiple-WL and All-BL Program,Program-Verify, and Read operations simultaneously with less power,latency, and disturbance.
 2. The HiNAND circuit of claim 1 wherein theBL-hierarchical structure comprises three levels including a first levelfor the N metal3 lines, a second level for the N metal2 lines laid outone level below the first level, and a third level for the N metal1lines laid out one level below the second level.
 3. The HiNAND circuitof claim 1 wherein each of the N metal3 lines comprises a firstparasitic capacitor associated with one GBL with a full length acrossall J Groups, each of the N metal2 lines comprises a second parasiticcapacitor associated with one SBL with a first length across all LSegments in one Group, each of the N metal1 lines comprises a thirdparasitic capacitor associated with one BBL with a second length acrossall K Blocks in one Segment, wherein the first length is about 1/J ofthe full length and the second length is about 1/L of the first length,correspondingly, the second parasitic capacitor having a capacitanceabout 1/J of that of the first parasitic capacitor and the thirdparasitic capacitor having a capacitance about 1/L of that of the secondparasitic capacitor and about 1/(J×L) of that of the first parasiticcapacitor, assuming same unit for all capacitors.
 4. The HiNAND circuitof claim 3 wherein each of the first, second, and third parasiticcapacitor is controlled at least by the N second GBL-select transistorsand the N second SBL-select transistors to be isolated from each otherto allow temporary charge storage in multiple local BBLs metal1 linesand SBLs metal2 lines in one or more Segments of one or more Groupsrepresenting sequentially loaded data from the Page Buffer circuit. 5.The HiNAND circuit of claim 3 wherein the first parasitic capacitor isconfigured to couple with the second parasitic capacitor and the thirdparasitic capacitor to share smaller amount of charges independentlycharged from the second power/Vss line and the third power/Vss line forreducing power consumption and latency during precharge for Program,Program-Verify, and Read operations.
 6. The HiNAND circuit of claim 1wherein the first power/Vss line is configured to discharge each of theN GBLs through all J Groups to Vss=0V by setting the first gate signalto Vdd=1.8V, the second power/Vss line is configured to discharge eachof the N SBLs in a currently selected Group to Vss by setting the thirdgate signal to Vdd, the third power/Vss line is configured to dischargeeach of the N BBLs in a selected Segment of the currently selected Groupto Vss by setting the fifth gate signal to Vdd.
 7. The HiNAND circuit ofclaim 6 wherein the third power/Vss line is configured to pre-chargeeach of the N BBLs in any selected Block in one or more selectedSegments of one or more selected Groups to a MV voltage up to 7V whilesetting the fifth gate signal up to 10V, setting the correspondingcommon source line to Vdd, setting a gate signal of the secondString-select transistor up to 10V to allow the MV voltage to pass andsetting a gate signal of the first String-select transistor to 0V toprevent leakage out of the selected Block, the N BBLs being isolatedfrom both the corresponding N SBLs and N GBLs at 0V by setting thesecond gate signal, the third gate signal, and the fourth gate signal to0V, for All-BL Program operation.
 8. The HiNAND circuit of claim 6wherein the second power/Vss line is configured to couple with aprecharge voltage ranging from Vdd up to 7V for charging the N SBLs andcorresponding N BBLs in one selected Segment of one or more selectedGroups by setting the corresponding third gate signal up to 10V, settingthe corresponding second gate signal to 0V, setting the correspondingfourth gate signal up to 10V, and setting the corresponding fifth gatesignal to 0V, for All-BL Read, Erase-Verify, and Program-Verifyoperations.
 9. The HiNAND circuit of claim 7 wherein each String of MNAND memory cells associated with the corresponding one of pre-charged NBBLs in the selected Block is latched to the MV-7V by setting the firstString-select transistor and the second String-select transistor to turnoff charge leakage paths, followed by turning off the third power/Vssline to 0V while setting the fifth gate signal to 0V.
 10. The HiNANDcircuit of claim 9 wherein the Page Buffer circuit is configured tosupply a N-bit logic page data with Vdd or 0V levels across the N GBLs,the N-bit logic page data being converted to a data pattern with MV or0V levels respectively at the N BBLs in the selected Block by firstsetting the second gate signal greater than Vdd with margin to sharecharges of the Vdd or 0V levels at the N GBLs with the corresponding NSBLs, followed by setting the fourth gate signal at Vdd to retain the MVlevel at part of the N BBLs if corresponding part of the N SBLs are atVdd level and to allow the remaining part of the N BBLs to drop to 0V ifthe corresponding part of the N SBLs are at the ground level, the datapattern then being held by switching the fourth gate signal from Vdd to0V.
 11. The HiNAND circuit of claim 10 wherein the Page Buffer circuitis configured to set a first data pattern with MV or 0V levels in afirst set of N BBL metal1 lines associated with a first set of N Stringsof HiNAND memory cells in a first Block and subsequently to at least seta second data pattern with MV or 0V levels in a second set of N BBLmetal1 lines associated with a second set of N Strings of HiNAND memorycells in a second Block, the first Block being selected from one or moreSegments of one or more Groups, the second Block being selected from analternative one of the one or more Segments of either the same oralternative one of the one or more Groups.
 12. The HiNAND circuit ofclaim 11 wherein the first N Strings of HiNAND memory cells comprises afirst page of cells at a first relative String location and the second NStrings of HiNAND memory cells comprises a second page of cells at asecond relative String location, the second page and the first pageconnecting to a same WL decoder, the first page of cells and the secondpage of cells being simultaneously programmed to store data respectivelyin accordance with the first data pattern and the second data patternindependently pre-set in a serial pipe-line.
 13. The HiNAND circuit ofclaim 8 wherein the N Strings of M NAND memory cells associated with thecorresponding charged N BBLs in the selected Block are subjected to theprecharge voltage ranging from Vdd up to 7V by setting gate signal ofthe second String-select transistor to smaller than Vdd and setting gatesignal of the top String-select transistor to 0V for keeping drainvoltage of each String of M NAND memory cells less than 0.5V to avoidcell-channel punch-through, followed by switching the gate signal of thefirst String-select transistor from Vdd to up to 10V for discharging thepart of the N Strings containing an On-cell with threshold level below apredetermined check voltage for Read/Program-Verify/Erase-Verifyoperation in a selected page to the corresponding common source line atground 0V while retaining the precharge voltage for remaining part ofthe N Strings containing an Off-cell in a page with threshold levelabove the predetermined check voltage in the selected page.
 14. TheHiNAND circuit of claim 13 wherein the part of the N Strings containingan On-cell in the selected page is configured to give the correspondingpart of N GBLs directly a 0V by setting the second gate signal to Vdd,and the remaining part of the N Strings containing an Off-cell in theselected page is configured to share the charges within eachcorresponding BBL metal1 line and SBL metal2 line respectively with eachcorresponding GBLs to provide a reduced GBL voltage as 1/J of theprecharge voltage or less by setting the second gate signal to Vdd, thereduced GBL voltages forming a data pattern represented by 1/J ofprecharge voltage or 0V levels associated with the selected page. 15.The HiNAND circuit of claim 14 wherein the Page Buffer circuit comprisesa Multiplier circuit to increase the reduced GBL voltage at 1/J ofprecharge voltage level to a value sufficiently large to be sensed andamplified by a Latch sense amplifier to a Vdd level latched to a datanode in the Page Buffer circuit, thereby converting the data patternrepresented by 1/J of precharge voltage or 0V levels associated with theselected page to a bit data in Vdd or 0V levels.
 16. The HiNAND circuitof claim 1 wherein each memory cell is a 2-poly LV float-gate NMOStransistor or 1-poly MONOS or SONOS charge-trapping NMOS transistorconfigured to be a SLC type with two threshold states, or a MLC typewith four threshold states, or a TLC type with 8 threshold states, or aXLC type with 16 threshold states.
 17. The HiNAND circuit of claim 1wherein each of the first String-select transistors, the secondString-select transistors, the BBL-select transistors, the firstSBL-select transistors, the second SBL-select transistors, the firstGBL-select transistors, and the second GBL-select transistors is amedium high-voltage 1-poly NMOS transistor or shorted-2-poly NMOStransistor with identical device type, characteristics, and breakdownvoltage.